The 1960s: The Nuclear-Free Zone, Oppression in Argentina and Molecules in Mexico

Illustration appearing in El Mercurio (Santiago, Chile), January 1962.

[Part 2 of 5]

In January 1962, Linus Pauling visited Chile in order to give an address at the Seventh International Summer School at the University of Concepción, and also to accept a certificate of honorary membership in the Chilean Society of Chemistry, one of many such honorary memberships that he received during his lifetime. While in Chile, the Paulings participated in the Summer School and also visited the Catholic University, the Technical University, the University of Chile in Santiago, the Experimental Station of the Institute of Agronomy in Chillán, and several other scientific institutions. Both Linus and Ava Helen gave lectures at many of the institutions they visited.

The theme of the Concepción Summer School was “The Man of Today, His Problems and His Future.” Pauling gave the opening address, titled “The Impact of Science on Man of Today and Man of the Future.” In this lecture, Pauling expressed his belief that mankind had accumulated enough knowledge to control the world instead of being controlled by it, but that with this knowledge came the power to destroy civilization. He thesis was a familiar one to those who had followed Pauling’s activism:

I believe in the philosophy of humanism – that the chief end of human life is to work for the happiness of man upon this earth, to work for the welfare of all humanity, to apply new ideas, scientific progress, for the benefit of all men – those now living and those still to be born.

One factor that works against the happiness of man, Pauling believed, is the variation in income which exists worldwide – a few people live in luxury while many suffer in poverty. He pointed out that economic injustice is “perpetuated by the oppressive powers of dictatorial governments,” and expressed his hope that these oppressive governments would give way to liberal and democratic governments.

In the same speech, Pauling also commented on the rapid progress of science and the new understanding of diseases caused by gene mutation, such as sickle-cell anemia and phenylketonuria. Some gene mutations, he added, are caused by the presence of radioactive materials released by nuclear bomb testing. Pauling continued, “I come now to the greatest of all the problems raised by the progress of science – the problem of preventing the destruction of civilization in a nuclear war.” He noted that the U. S. was in possession of 100,000 megatons of bombs, while only 20,000 megatons would be needed to decimate Russia. Likewise, Pauling estimated that the Soviets had produced 50,000 megatons of bombs, but that just 10,000 would be enough to destroy the U. S.

Pauling stressed to his Chilean audience that a nuclear war would not only destroy the U. S. and Russia, but would affect the Southern Hemisphere as well, in the form of nuclear fallout and genetic mutations. The only way to proceed in order to save the human race, Pauling concluded, was through complete disarmament, which must be supported not only by nations, but by individual people as well. “The survival of the whole human race now depends upon whether or not we can work together for the common good,” he concluded, stressing that world peace can only be achieved if nations adopt the moral values of individuals. After spending almost three busy weeks in Chile, Linus and Ava Helen returned home to California on January 22.

When Hurricane Flora hit Cuba in 1963, pounding the country for four days, Pauling attempted to visit in order to provide emergency disaster relief. However, the U.S. government did not allow him to travel to the Communist country, so instead, he and Ava Helen had to settle for supporting the Cuban people from afar. Pauling was also a member of Fair Play for Cuba, which was an organization that protested the trade embargo that the U.S. had placed on Cuba.

That same year, Linus was invited by Professor N. Matkovsky, of the International Institute for Peace in Vienna, to visit the leaders of various Latin American countries. The purpose of the visit was to support the presidents of Brazil, Bolivia, Ecuador, Chile and Mexico in their publication of a declaration to make all of Latin America a nuclear-free zone. The declaration had been signed by the five countries on May 1st, 1963, and would lead to the ratification of the Treaty of Tlatelolco in 1967, which would prohibit nuclear weapons in Latin America and the Caribbean, and include thirty-three parties. Linus and Ava Helen accompanied Professor Matkovsky on his mission as guest observers, but they also had the opportunity to meet with the leaders of a few countries. Delegations took place on August 15 in Rio de Janeiro; the Paulings stayed in Brazil for about 3 days, and flew to Chile on the 20th.

Linus Pauling and Arturo Illia, as published in Consejo Argentino de la Paz, October 1963.

Later in August, Pauling spoke with Arturo U. Illía, the President-elect of Argentina, to address the prevention of a devastating war and the preservation of peace in the world. A few days after he spoke with Illía, Pauling gave a speech to Pharmacy and Biochemistry faculty at the National University of Argentina entitled “Molecular Structure and Evolution.”

A month after the Paulings returned home, they learned that more than fifty women workers for peace in Rosario, Argentina had been arrested, some of them individuals to whom the Paulings had spoken during their visit to Buenos Aires. Linus wrote a letter to Illía, asking him to take action on the arrest of the women. In the letter, Pauling named a few of the women that he and Ava Helen had met and demanded that they and the rest of the women be set free. He also expressed concern about the extreme action the government had taken in recent weeks.

I have been hoping that, after a period during which the authorities of the Republic of Argentina suppressed the rights of individual human beings and carried out many oppressive actions, your nation would take its place among the civilized nations of the world, would recognize the rights of individual human beings, and would abandon the dictatorial and oppressive policies that are characteristic of governments in backward nations.

He echoed his appeal in letters to the current President at the time, Arturo Mor Roig, and to Raul Andrada, a judge in Argentina’s federal court, but his entreaties went ignored.

Pauling's greeting to the National School of Chemical Sciences, Mexico, as reprinted in Gaceta de la Universidad, July 13, 1964.

Pauling’s next visit to Latin America came about in May 1964, to help celebrate the Congress of the Centenary of the National Academy of Medicine in Mexico City. At the Academy, Pauling gave a speech as the guest of honor, “Abnormal Hemoglobin Molecules and Molecular Disease.” In this talk, he first established that the molecules that make up our DNA are the most important molecules in the world, since “[t]he pool of human germ plasm is a precious heritage of the human race.” Pauling then discussed various molecular diseases, such as phenylketonuria, which was responsible at the time for one percent of the institutionalized “mentally defective” individuals in the U. S.

According to Pauling, the disease occurs when both the mother and the father of an infant carry a gene for phenylketonuria, in which case the offspring has a fifty percent chance of inheriting the defective gene. If the infant does inherit the gene, he or she would have it in a double dose, which would inhibit him or her from being able to manufacture the enzyme that catalyzes the oxidation of phenylalanine to tyrosine. As a result, if the infant ate a food containing protein, phenylalanine would build up in the bloodstream and interfere with the growth and function of the brain. The only way to treat this disease, Pauling continued, is to eat a diet of protein hydrosylate from which most of the phenylalanine has been removed. This treatment must be carried out within the first year of life, or mental retardation occurs, and the diet must be followed for the rest of the patient’s life.

After detailing the dangers and the solutions for phenylketonuria, Pauling held that, likewise, other molecular diseases could be controlled, such as sickle-cell anemia. Sickle-cell anemia is similar to phenylketonuria in that it is a molecular disease, but different in that individuals who carry only one sickle-cell gene, called heterozygotes, are protected against malaria.

Pauling rounded out his trip to Mexico by delivering another talk, titled “Molecules and Evolution,” at the National School of Anthropology.  Pauling also spent a great deal of his time in Mexico discussing the devastating effects of nuclear war, repeating his conviction that the United Nations should have custody and control of radioactive substances produced by the United States and Russia.  This work done, the Paulings left Latin American behind for a while, not returning to the region until a trip to Chile in 1970.  That visit will be the subject for our next post in this series.

Chris Hables Gray, Resident Scholar

Dr. Chris Hables Gray

Dr. Chris Hables Gray, professor at the Union Institute and University and lecturer at the University of California, Santa Cruz, is the fourth individual this year to complete a term as Resident Scholar in the Special Collections & Archives Research Center.  Dr. Gray is a self-described “anarchist, feminist, post-modernist” who has written widely on a number of subjects, with a particular emphasis on cyborgs and evolution.

Gray visited Corvallis to examine the Paul Lawrence Farber Papers and the Ava Helen and Linus Pauling Papers, spurred by a keen interest in tracing the development of Pauling’s thinking on evolution.  His provocative Resident Scholar presentation, titled “Linus Pauling and the Temptation of Evolutionary Ethics,” generated a great deal of thoughtful discussion among those who gathered to hear him speak.

Gray’s thesis was that, in at least two instances, Linus Pauling gave in to what Paul Farber termed “the temptations of evolutionary ethics.”  Farber, a historian of science and emeritus chair of the OSU History Department, defined this temptation as the impulse to use science as a basis for a full system of normative ethics.  Gray is sympathetic to Farber’s warnings against this impulse as, in his view,

Culture is not different from nature.  Human culture is natural.  It is evolved, as much as the behavior of mockingbirds or ants.  All of life is evolved.  The natural/biological vs. cultural distinction is not only wrong, it is dangerous.  [On the same token], humans are not rational.

As an extension of this postulate, Gray offered this thought, which was fundamental to his presentation

I don’t think evolutionary science will ever provide a base for a system of ethics.  The ideas and actions behind the Holocaust are as natural as those behind the Civil Rights movement.  All that humans do is natural….Farber is right that evolutionary science cannot give us a normative ethics, a complete system of ethics.  It cannot show what should be ethical, but it can show what is possible and what is impossible.  It can help us in our ethical reasoning.

During his stay in Corvallis, Gray traced Pauling’s thinking on evolution from his earliest documented years, noting a particularly optimistic Junior Class Oration in which the future scientific great “makes of evolution a religion.”  As time moved on, Pauling’s thoughts on the topic changed somewhat, his optimism tempered by the realities of the atomic age.  Instead of a religion, evolution became a morality.  Likewise, man was no longer destined to evolve into a superman, but rather was part of a superorganism, “humankind,” whose greatest attributes – as Pauling noted in 1959 – were “sanity (reason), and morality (ethical principles.)”

For Pauling the concept of morality was firmly rooted in Albert Schweitzer’s principle of “minimization of suffering,” and it is here that he began to fall prey to the temptations of evolutionary ethics. Most glaring was Pauling’s advocacy of negative eugenics in the mid- to late-1960s.  As Gray noted

Pauling saw reality as based on molecules, and so diseases were molecular….His work on sickle-cell anemia was framed in this way. Once he realized that it was a genetic disease he put forward some startling solutions… [including the tattooing of phenotype information on people's foreheads] enforced genetic testing and abortions…even though dietary and other treatments for sickle cell anemia were known and effective. Eventually he stopped raising this issue. We don’t know why for sure, but we can assume he realized it was not a popular approach to the problem of genetic disease.

Gray also submitted Pauling’s interest in vitamin C, especially as a possible treatment for cancer, as another example in which his evolutionary thinking went astray.

The reasoning behind Pauling’s belief that humans did not consume enough Vitamin C was based on evolutionary science. Roughly half the primates, including humans and our closest cousins, cannot synthesize vitamin C, an ability that all plants and almost all animals have. His theory was that the ancestral primate lost the ability to synthesize C when in an environment with plentiful dietary C. Then, as humans moved into other environments with less dietary C, deficiency diseases and conditions, such as a degraded immune system…resulted – and not just scurvy, but long term conditions and even cancer.

While Gray conceded that there is some validity to this argument, he found Pauling’s larger thesis to be “less than convincing.”

…numerous studies have failed to show that all, or even most, humans have a massive Vitamin C deficit. It is true that C can help limit the severity of colds, that it helps in some healing, and has other benefits. But the massive positive effects of massive doses of C have not proven to be as helpful as Pauling claimed.

Gray concluded that

we have to be more careful that Pauling in applying evolutionary thinking to ethics….if we take evolution seriously we have to let go of totalizing schemes for perfecting humanity, as much as the dream of perfection appeals to young chemistry students and profoundly moral famous scientists alike. But evolutionary science can be useful in our quest for a better, more moral, world.

Because of the great diversity of humans…especially as evolved culture allows for such a wide range of variation, and “conscious” evolution, no totalistic ethical system based on human altruism or any other quality is viable. Altruism has certainly evolved in humans, as has selfishness, cruelty, and social pathology. Inherited traits are often not universal, which makes sense in that variation is the key to evolution’s power. But this also means that any ethical system will have to be imposed on some people, even if it is a “biological” fit for the majority. And since all of us have many layers of moral reasoning and ethical impulses, often contradictory, and that humans continue to evolve and a very fast rate thanks to the Lamarkian power of culture, we will never have a perfect ethics.

For more on the Resident Scholar Program, please visit this page, which, among other details, includes links to the profiles that we have written of all past scholarship recipients.

On the Formation of Antibodies

By the 1940s, Linus Pauling’s research interests had expanded to include many subjects generally outside the purview of a typical chemist. In particular, immunology was rapidly becoming a fascination of his – one that would come to devour more and more of his time both in and out of the lab. For Pauling, much of the human body could be viewed as a gigantic set of very complicated chemistry problems, and he derived great joy from being able to solve some of these problems. Among his most important immunological discoveries were his elucidation of the role that hemoglobin plays in sickle cell anemia and his theory of antibody formation.  The latter is the topic of today’s post.

In 1940 Pauling published a paper – now his ninth most cited – in the Journal of the American Chemical Society on the subject of antibodies and antigens. This manuscript, titled “A Theory of the Structure and Process of Formation of Antibodies” is fundamentally based around one important assumption that Pauling made about antibody structure, “…that all antibody molecules contain the same polypeptide chains as normal globulin, and differ only in the configuration of the chain; that is, in the way that the chain is coiled in the molecule.”

Antibodies are protein molecules that play an extremely important role in the human body. Their main function is to identify and neutralize foreign objects, called antigens, that have been taken up by the body. Antigens come in many varieties, including high-molecular-weight carbohydrates, lipids, pollen and bacterial cells. It is important to note too that only antigens marked by the body’s systems as “foreign” will set off an antibody response; antigens marked as “self” are tolerated by the body.

Pauling with Dan Campbell, a primary colleague in Pauling's antibody work.

Antigens play an important role in Pauling’s theory, which argues that antigens alone determine the configuration of a specific portion of the antibody molecule. For example, without the presence of an antigen, a normal globulin protein will be synthesized. In the presence of an antigen however, a specific antibody will be produced, a portion of which will be complementary in structure to the antigen that in question. In describing this process, Pauling’s paper first details the four steps that occur in the formation of a normal globulin molecule, which are summarized below.

1. The polypeptide chain is synthesized. The two ends of the chain are free, but the center of the chain is still attached at the site of synthesis.
2. The ends coil into either their most stable, or another very stable, configuration. Hydrogen bonds and other weak forces between amino acids in the polypeptide chain stabilize the two ends.
3. The center of the chain is freed from the site of synthesis.
4. The center coils into its most stable configuration, and the globulin molecule is completed.

Because antibodies are simply modified globulin molecules, the process for their formation is closely related to that of globulin. Summarized below then, are Pauling’s six steps of antibody formation.

1. An antigen is held in place at the site of antibody production and the antibody is synthesized around the antigen molecule.
2. The ends of the newly synthesized antibody coil into a configuration complementary to groups on the antigen and attach to these complementary groups.
3. The center of the chain is freed from the site of synthesis, causing one of two things to happen. If the forces between the ends of the chain are sufficiently strong, both ends will continue to be attached to the antigen, and the antibody will never be completed.
4. If they forces between the ends of the chain and the antigen are weak, one end will dissociate from the antigen.
5. Assuming one end of the chain dissociates from the antigen, the center of the chain coils into its most stable configuration, making a complete antibody.
6. Eventually, the antibody will dissociate from the antigen and float away.

To summarize, Pauling’s theory of antibody formation argues that every antibody has the same configuration in the center of its polypeptide chain, and that the configuration of the ends of the chain are dependent on which antigen is present at the time of the antibody’s synthesis.  In present day, even with our better understanding of antibody synthesis, the core principles of Pauling’s theory – most prominently the idea that each antibody shares a common structure – remain sound.

The entirety of Pauling’s manuscript is available here.  In it, he discusses other topics related to his theory, including the formation of different structures based on antibody to antigen ratios, the characteristics that define a molecule or substance as an antigen, and the compatibility of his theory with experimental results. For more information on Pauling’s immunological work, visit It’s in the Blood: A Documentary History of Linus Pauling, Hemoglobin, and Sickle Cell Anemia.

An Era of Discovery in Protein Structure

Linus and Ava Helen Pauling, Oxford, 1948.

[The Paulings in England: Part 4 of 5]

Though metals were consuming a good portion of his time during his fellowship at Oxford, Linus Pauling’s other projects never strayed far from his thoughts.  High on the list were the mysteries of proteins, whose structures and functions were slowly starting to be unraveled.

Pauling’s interest in proteins was spurred in the mid-1930s when the Rockefeller Foundation began to look most favorably upon the chemistry of life when deciding where their grant money would go. Early on, Pauling set out to tackle hemoglobin and though his affair with the molecule lasted for the remainder of life, Pauling certainly didn’t limit himself to the study of just one protein.

At a time when most were looking at proteins from the top down, trying to sort out the complicated data produced by an x-ray diffraction photograph of an entire protein, Pauling was working from the bottom up, in the process determining the structures of individual amino acids – the building blocks of proteins.

A specific protein that kept coming back into view over the years was keratin. In the 1930s, the English scientist William Astbury had studied the structure of wool, which along with hair, horn, and fingernail is made up primarily of this enigmatic protein, keratin. Astbury proposed that the structure was akin to a flat, kinked ribbon, but Pauling disagreed. “I knew that what Astbury had said wasn’t right,” Pauling recalled, “because our studies of simple molecules had given us enough knowledge about bond lengths and bond angles and hydrogen-bond formation to show that what he said wasn’t right. But I didn’t know what was right.” Pauling attempted to construct a model at the time, but could not match his structure to the measurements dictated by Astbury’s blurry x-ray diffraction images. Pauling wrote the project off as a failure and continued pursuing other interests.

In 1945 Pauling found himself seated next to Harvard medical Professor William B. Castle on a railroad journey from Denver to Chicago. Castle was a physician working on the nature of sickle cell anemia and the conversation that he shared with Pauling planted a seed in Pauling’s mind about the cause of this debilitating disease.

In the bodies of those suffering from sickle cell anemia, red blood cells assume a sickled shape when they are in the deoxygenated venous system but retain their normal flattened disk shape in the oxygen-rich arterial system. Noting this, Pauling suggested that perhaps the source of the problem could be a defect in the oxygen-carrying protein itself: hemoglobin.

Amidst his travels in Europe, Pauling continued to act on this idea as maestro from afar, directing the scientists in his Caltech laboratory to continue searching for differences in the hemoglobin of normal and sickled cells. In the meantime, he sought out and communicated new ideas gleaned from meetings such as the Barcroft Memorial Conference on Hemoglobin, held at Cambridge in June 1948. Pauling’s research team, in particular Harvey Itano and S. Jonathan Singer, were able to show experimentally that his hunch had been right, and less than a year after his return to Pasadena a paper was published that established sickle cell anemia as the first illness to be revealed as a truly molecular disease.

Linus and Peter Pauling at the model Bourton-on-the-water, England. 1948.

While in England, Pauling had occasion to interact closely with a number of scientific greats.  Among these were his close friend Dorothy Crowfoot Hodgkin, who is credited as a pioneer in the development of protein crystallography and was the winner of the 1964 Nobel Prize for Chemistry.  Likewise, Pauling conversed with Max Perutz, a protege of Sir William Lawrence Bragg‘s at the Cavendish Laboratory at Cambridge, who would go on to discover the structure of hemoglobin and receive the Nobel Prize for Chemistry in 1962.  While fruitful in many respects, these interactions served to increase Pauling’s feelings of urgency as concerned the race to determine the structure of proteins.

Bragg shared the 1915 Nobel Prize in Physics with his father for their early development of X-ray crystallography, and though there existed a long-standing scientific rivalry between Pauling’s and Bragg’s laboratories, it wasn’t until Pauling saw, with his own eyes, the work that was being done that he admitted he was “beginning to feel a bit uncomfortable about the English competition.” As he wrote to his colleague Edward Hughes back at Caltech

It has been a good experience for me to look over the x-ray laboratory at Cambridge. They have about five times as great an outfit as ours, that is, with facilities for taking nearly 30 x-ray pictures at the same time. I think that we should expand our x-ray lab without delay.

This realization prompted Pauling to get researchers in his lab started on work with insulin – an arduous and complicated process that required sample purification and crystallization prior to x-ray investigation. In relaying research findings from English scientists working on insulin to his partners back in Pasadena, Pauling intimated that

It is clear that there is already considerable progress made on the job of a complete structure determination of insulin. However, there is still a very great deal of work that remains to be done, and I do not think that it is assured that the British school will finish the job. I believe that this is the problem that we should begin to work on, with as much vigor as possible, under our insulin project.

Little did Pauling know that, while laying in bed, using little more than a piece of paper, a pen and a slide rule, he would soon make a major breakthrough in protein chemistry on his own.

A Theory of the Denaturation of Proteins

Alfred E. Mirsky, 1960s

In 1935, as a result of being prompted toward the biological sciences in order to keep his Rockefeller Foundation funding, Linus Pauling began his research on proteins. Hemoglobin, the oxygen-binding agent in blood, was his first target; but as he became more aware of the complex nature and diversity of proteins, he began contemplating broader topics related to the subject – one of which was the theory of protein denaturation.

In the spring of 1935, Pauling traveled to the Rockefeller Institute in New York City, where he met Dr. Alfred Mirsky. Mirsky was a Rockefeller scientist who had previously conducted denaturation research, and because of his new interest in the subject, Pauling arranged for Mirsky to spend fifteen months working with him at Caltech. Although initially hesitant, Mirsky eventually agreed, and the pair began collaborating in the summer of 1935.

In July 1936, the duo’s paper, titled “On the Structure of Native, Denatured, and Coagulated Proteins” was published in the Proceedings of the National Academy of Sciences.  In this paper, the authors loosely describe protein denaturation as “the loss of certain highly specific properties by the native protein,” and provide examples of the types of changes that have been experimentally observed.

In so doing, Pauling and Mirsky point out that while many proteins in their native form have been crystallized, no denatured protein exist in this state. Likewise, in proteins that act as enzymes, denaturation causes a disappearance of the enzymatic activity.  And one fact that was of particular interest to Pauling was that the process of denaturation is occasionally reversible.

Early Pauling notes on the characteristics of protein denaturation, ca. 1935

As researchers are now aware, any given protein has a certain structure – or rather, four different structural levels – that needs to be maintained in order for the molecule to function correctly. Although this crucial bit of information was still unknown at the time of Pauling and Mirsky’s research, the authors essentially touch on this exact detail in their 1936 paper:

Our conception of a native protein molecule (showing specific properties) is the following. The molecule consists of one polypeptide chain [the amino acid sequence] which continues without interruption throughout the molecule (or in certain cases, of two or more such chains); this chain is folded into a uniquely defined configuration, in which it is held by hydrogen bonds…

The collaborators further posited that, as a result of this “structure equals function” characteristic of proteins, denaturation is “characterized by the absence of a uniquely defined configuration” and can be accomplished in a number of different ways, including heating, subjection to ultraviolet light, or an attack by certain reagents.

In presenting their theory of denaturation, Pauling and Mirsky associated both the heating of the protein and its treatment with certain reagents, as leading to the disruption or complete rupturing of hydrogen bonds.  From there they pointed out that ultraviolet light is not able to break a sufficient quantity of hydrogen bonds, and therefore must affect the molecule differently – an impact which they predicted to be an attack on the main polypeptide chain. Consequently, they suggested that denaturation caused by ultraviolet light was irreversible, while methods that disrupt the more easily re-formed hydrogen bonds would be reversible.

Although Pauling and Mirsky weren’t correct in every aspect of their denaturation theory (ultraviolet light does not disturb the polypeptide chain, and denaturation involves more than just the disruption of hydrogen bonds), it provided a strong start for further work.  The Pauling-Mirsky theory also touched on many details of the structure of proteins in their native forms, a field of inquiry that would not be completely elucidated for many years to come.

For more information on Linus Pauling, please visit the Linus Pauling Online portal. For more information on Alfred Mirsky, visit his key participants page within the It’s in the Blood! A Documentary History of Linus Pauling, Hemoglobin, and Sickle Cell Anemia site.

Pauling’s First Hemoglobin Publications: Understanding Oxygen Binding

Pastel drawing of the hemoglobin structure, by Roger Hayward. 1964.

“You know, hemoglobin is a wonderful substance. I like it. It’s a red substance that brings color into the cheeks of girls, and in the course of my hemoglobin investigation I look about a good bit to appreciate it.”

– Linus Pauling, March 30, 1966

Seventy-five years ago, in 1935, Linus Pauling began publishing his research on the protein hemoglobin with a set of papers titled “The oxygen equilibrium of hemoglobin and its structural interpretation” appearing in Science and the Proceedings of the National Academy of Science .

In the fall Pauling extended this work and began collaborating with newly minted Caltech Ph. D. Charles Coryell, on the problem of the binding of oxygen to hemoglobin in the formation of the compound oxyhemoglobin. In April 1936, the duo published a paper specifically devoted to the subject, “The magnetic properties and structure of hemoglobin, oxyhemoglobin, and carbonmonoxyhemoglobin,” an important article which appeared in PNAS.

In order to better understand this early hemoglobin work, it is important to first discuss some of the basics of the hemoglobin molecule. Hemoglobin is a major protein component in the cytoplasm of red blood cells, and is made up of two distinct parts – the heme and the globin. Its primary function is to facilitate gas exchange: it picks up oxygen in the lungs, carries it to the tissues, and returns to the lungs in order to expel the carbon dioxide produced in the tissues.

There are four hemes per hemoglobin molecule, and each is made up of a single iron atom surrounded by a porphyrin ring. Each heme has the ability to bind to a single oxygen dimer, therein giving hemoglobin the capacity to bond with four molecules of O₂. The globin is the main protein component of the molecule. Carbon dioxide, rather than competing with oxygen for a binding site at the heme, instead binds to the globin.

Charles Coryell and Linus Pauling. 1935.

In their 1936 paper, Pauling and Coryell tackled the question of how oxygen binds to hemoglobin by looking at the molecule’s magnetic behavior, using an experiment involving bovine blood and magnets.  In a 1976 interview, Pauling provided this description of their experimental design.

It occurred to me that the same magnetic methods that we had been using to study simple compounds of iron, in order to determine the bond type, could be used to study the hemoglobin molecule. One of my students, Charles Coryell, and I, then got some blood, cattle blood, and put it into an apparatus. It consisted of a balance, which we had fitted out in such a way that a wire was suspended from one arm of the balance through a hole in the base of the cabinet, and held a tube. This tube was placed between the poles of an electromagnet. We filled it with blood, oxygenated blood, and balanced it to measure its weight. Then we passed an electric current through the coils of wire and the apparent weight changed.

From the experimental results, the pair found that oxyhemoglobin contains no unpaired electrons, although free oxygen molecules contain two, and each heme contains four. This was something of a surprise as, quoting from the paper,  “It might well have been expected, in view of the ease with which oxygen is attached to and detached from hemoglobin, that the oxygen molecule in oxyhemoglobin would retain these pair of electrons.”

In spite of this possibly more intuitive expectation, Pauling had earlier theorized that oxygen binds to hemoglobin covalently, a prediction which the experiment confirmed. Indeed, it was found that “the oxygen molecule undergoes a profound change in electronic structure on combination with hemoglobin,” and binds to the iron atom in the heme covalently.

Pastel drawing of Hemoglobin at 100 angstroms, 1964.

This was, however, only one of the striking discoveries that surfaced out of this research.  In a deoxygenated hemoglobin molecule, the bonds between iron and the four porphyrin nitrogen atoms surrounding it are ionic. Nonetheless, upon the binding of oxygen, these bonds become covalent, a rather dramatic change. Pauling and Coryell were keen to point this out:

It is interesting and surprising that the hemoglobin molecule undergoes such an extreme structural change on the addition of oxygen. Such a difference in bond type in very closely related substances has been observed so far only in hemoglobin derivatives.

Clearly something of consequence was being observed.  In their conclusion, the authors noted as much.

It is not yet possible to discuss the significance of these structural differences in detail, but they are without doubt closely related to and in a sense responsible for the characteristic properties of hemoglobin.

Linus Pauling’s work with hemoglobin continued on and off until his death in 1994, and led to a number of important discoveries – most prominent among them the molecular basis of sickle cell anemia. For more information on Linus Pauling’s hemoglobin research, please visit the website It’s in the Blood! A Documentary History of Linus Pauling, Hemoglobin, and Sickle Cell Anemia.

Remembering Harvey Itano

Portrait of Harvey Itano, 1954. Image courtesy of the Caltech Institute Archives.

“The discovery by Dr. Itano of the abnormal human hemoglobins has thrown much light on the problem of the nature of the hereditary hemolytic anemias, and has changed these diseases from the status of poorly understood and poorly characterized diseases into that of well understood and well characterized diseases.”

-Linus Pauling, 1955.

We were saddened to learn of the death of Harvey A. Itano, emeritus professor of pathology at the University of California, San Diego.  Dr. Itano passed away on May 8, 2010 at the age of 89.

Best known professionally for his work on sickle cell anemia, Itano’s early personal history makes for fascinating reading.  According to this excellent obituary issued by UCSD

Itano was born in Sacramento, CA on November 3, 1920, the oldest of four children of Masao and Sumako Itano, originally of Okayama-ken, Japan.  A star student at UC Berkeley, he graduated in 1942 with highest honors in chemistry.  He was unable to attend his own graduation ceremony, because he and his family were confined to internment camps established after the bombing of Pearl Harbor for the detention of Japanese and Japanese-Americans living in the western US.  In recognition of his outstanding achievements as a student, having earned the highest academic record in his class, then-UC President Robert Gordon Sproul personally awarded him the University Medal during his internment.

[...] He was released from the camp on July 4, 1942, the first of the Nisei (second generation Japanese-Americans) to be released to attend colleges and universities.  He attended the St. Louis School of Medicine, where he earned his MD in 1945 before continuing his studies at California Institute of Technology, earning a PhD in Chemistry and Physics in 1950.

It was at Caltech that Itano came into contact with Linus Pauling, his major professor during his doctoral studies and research colleague for the duration of a four year post-doctoral stint in Pasadena.  Over the course of this time period, Itano, Pauling and their collaborators made a series of significant contributions to the field of molecular biology.

Most prominent among these contributions was a 1949 paper published in Science, titled “Sickle Cell Anemia, A Molecular Disease.”  Authored by Pauling, Itano, S. Jonathan Singer and Ibert C. Wells, the paper presented experimental evidence in support of Pauling’s theory that sickle cell anemia could be traced to significant abnormalities in the hemoglobin molecules of those suffering from the disease.  The paper was quickly recognized to be the first solid proof of the existence of a “molecular disease.”

In his book Force of Nature, Pauling biographer Thomas Hager comments on the importance of this discovery.

People had theorized in broad terms about the molecular basis of disease before, but no one had ever demonstrated it the way Pauling’s group did….By pinpointing the source of a disease in the alteration of a specific molecule and firmly linking it to genetics, Pauling’s group created a landmark in the history of both medicine and molecular biology.

Itano spent much of his long career furthering the breakthroughs signaled in the 1949 paper.  Among other achievements, he developed a “rapid diagnostic test” for sickle cell anemia which would quickly indicate whether or not a given blood sample would sickle.  With S. J. Singer, Itano also described the condition of sicklemia, an intermediate and less severe stage of sickle cell anemia in which a patient’s blood contains a mix of normal hemoglobin and sickled hemoglobin cells.

Harvey Itano and Linus Pauling. 1980s.

Linus Pauling held Itano in high regard, both as a scientist and as a person.  In a lengthy award nomination that Pauling composed for Itano in 1955, Pauling describes the specifics of Itano’s contribution to the team’s molecular disease breakthrough while noting his “great natural ability and thoroughly sound training in chemistry and related sciences as well as in medicine.”  Of the man, Pauling wrote

His success must also be attributed in part to his excellent personality.  He is quiet and pleasant in manner, and is well liked by all of his associates.  During his eight years at the California Institute of Technology he made many friends, and he was uniformly successful in effective collaboration with a number of co-workers.  He is original, clearheaded, keen, and critical in his scientific work.

Itano maintained a keen interest in his rich genealogical background, and those who wish to learn more about his story are encouraged to visit the Itano family history website.  A great deal more about Itano’s role in the sickle cell anemia and molecular disease story is likewise available at It’s in the Blood!  A Documentary History of Linus Pauling, Hemoglobin and Sickle Cell Anemia.

Mastering Genetics: Pauling and Eugenics

Illustration from Medical World News article, "Sickle Cell Anemia" December 3, 1971.

“I have suggested that the time might come in the future when information about heterozygosity in such serious genes as the sickle cell anemia gene would be tattooed on the forehead of the carriers, so that young men and women would at once be warned not to fall in love with each other.”
-Linus Pauling, August 15, 1966

After declaring sickle-cell anemia to be a “molecular disease” in the late 1940s, Pauling spent more than a decade describing the cause of the disease and the significance of its unique origins to his fellow academics. Unfortunately, though interested, his colleagues seemed more concerned with the concept of a molecular disease than its real world application in genetics and medicine. Beginning in 1958, Pauling became a vocal advocate of genetic counseling, focusing especially on sickle-cell anemia among the African American population. His efforts went largely unnoticed by both researchers and the general public alike.

Frustrated with his unsuccessful endorsement of genetic counseling, Pauling chose to take his ideas a step further. In 1962, Pauling began a public campaign in support of negative eugenics – the restriction of human breeding and childbirth as a means of minimizing the sharing of hereditary diseases. He advocated genetic testing as a requirement for obtaining a marriage license. Perhaps even more controversial, Pauling recommended placing legal restrictions on marriage and childbirth between carriers of hereditary diseases.

Listen: Pauling on Marriage Tests and the Disclosure of Genotype Information

Pauling recognized the difficulty of controlling and monitoring a program of this magnitude. Without being able to easily identify carriers of various diseases, the public could not effectively choose sexual partners, thus lessening the potential effectiveness of employed eugenics. As a solution, in the late 1960s, Pauling began suggesting a means of visibly marking disease carriers – a tattoo on the forehead, clearly marking the individual as the carrier of a specific disease. Not surprisingly, this suggestion engendered a great deal of criticism. He was compared with the likes of Hitler by his critics who drew parallels between the proposed tattoo and the yellow star worn by Eastern European Jews during the reign of the Nazi party.

In reflecting upon Pauling’s stance, it is important to note that he was not interested in positive eugenics – the manipulation of genetic combinations as a means of developing a superior human. Rather, he intended only to minimize human suffering and found the idea of building a “super race” highly undesirable. Pauling was also a critic of the concept of genetic purity. He was concerned with purifying the human gene pool of harmful diseases, but he was not motivated by the desire to manipulate intelligence, appearance, strength, etc.

Pauling insisted that his ideas, though extreme, were meant to decrease human suffering rather than to segregate and belittle. Though Pauling faced many critics, he did have supporters as well. Nobel laureate Sir Peter Medawar agreed with Pauling, famously stating,

It is humbug to say that such a policy violates an elementary right of human beings. No one has conferred upon human beings the right knowingly to bring maimed or biochemically crippled children in the world.

During the 1960s, Pauling’s critics began discussing the effect that negative eugenics could have on evolution. Roderic Gorney, a psychiatrist, argued that over a long enough period of time, eugenics could redirect and even supersede the process of natural selection.

For example, consider the effect of negative eugenics in relation to sickle-cell anemia. An individual with sickle-cell anemia has two sickle-cell alleles. Typically, sufferers of sickle-cell anemia are plagued by a host of related health problems, often leading to an early death. Some individuals, however, possess only one sickle-cell allele. These individuals exhibit some sickling of the blood cells, but are otherwise able to live normal, healthy lives. Because sickle-cell anemia is a hereditary disease, it is passed on in Mendelian fashion. As a result, a person with a single sickle-cell allele, when paired with a healthy individual, has a 25% chance of giving birth to a child with one sickle-cell allele. When paired with another single-trait individual, there exists a 50% chance that a child will have one sickle-cell trait, and a 25% chance that the child will be afflicted with full sickle-cell anemia.

Gorney argued that sickle-cell anemia, if left alone, would eventually be removed from the human gene pool. He explained that, because individuals suffering from sickle-cell anemia rarely live to procreate, few instances of sickle-cell anemia are added to the collective gene pool. Similarly, a single-allele individual has a statistical opportunity to produce children with sickle-cell anemia when paired with another carrier. These offspring will die at a young age, further reducing the number of carriers present in the next generation. As a result, over a period of time, the number of sickle-cell carriers would decrease to nothing.

Negative eugenics, however, allows sickle-cell carriers to identify other carriers and instead mate with healthy individuals, producing more children with a single sickle-cell allele. If this process were to continue indefinitely, more and more humans would be heterozygous for sickle-cell anemia, rendering it virtually impossible for natural selection to remove the disease from the human gene pool. This argument could, in fact, be applied to any similar hereditary disease.

"Bad Genes and Marriage," New York Post, October 21, 1968.

Pauling acknowledged Gorney’s concerns but countered that, without eugenics, preventative medicine would have a much more damaging effect. Pauling felt that modern medicine (antibiotics, chemotherapy, prescription drugs, etc.) helped prolong the lifespan of sick or diseased individuals, sometimes allowing them to procreate and pass along hereditary diseases. As such, modern medicine was effectively undoing natural selection, leaving negative eugenics as the best hope for maintaining a balanced, healthy population.

In the early 1970s, Pauling began to run into trouble. His main focus throughout his eugenics campaign was the elimination of sickle-cell anemia, a disease that had originated in Africa where it became common among the native population because of its ability to prevent malaria. When slave traders brought African captives to North America, sickle-cell anemia was introduced to the United States. Due to racial segregation and the social mores that developed in the U.S. over the intervening 300 years, very few individuals outside of the African American population were afflicted with sickle-cell disease. For these reasons, Pauling advocated blood testing among the African American population. As the Civil Rights movement gained momentum, Pauling’s suggestions were seen as racist, and even as an attempt to cast African Americans as genetically inferior and meriting legal restrictions on their rights to marriage and procreation.

Frustrated and embarrassed by the criticism that he was receiving, Pauling fell silent on the topic of eugenics. In the past, when faced with heavy opposition, Pauling had always held his ground. But this episode was different. By the end of 1972, Pauling had given up his negative eugenics campaign and turned to other means of improving the human condition.

For more information on Pauling and his work with genetics, visit “It’s in the Blood! A Documentary History of Linus Pauling, Hemoglobin and Sickle Cell Anemia” or Linus Pauling Online.

The Theory of the Molecular Evolutionary Clock

Dr. Emile Zuckerkandl, 1986.

“It thus appears possible that there would be no evolution without molecular disease.”
-Linus Pauling. “Molecular Disease, Evolution and Genic Heterogeneity,” 1962.

In the early 1960s, Linus Pauling and Emile Zuckerkandl, a French postdoctoral fellow who had arrived at Caltech in 1959, began researching the characteristics of hemoglobin extracted from a number of different species of animals. Zuckerkandl used a technique called fingerprinting, a process taught to him by a Caltech graduate student named Richard T. Jones, to create patterns of the amino acid sequences in each hemoglobin molecule.

[In her Master of Science thesis (pdf link), Dr. Melinda Gormley described fingerprinting, which was invented by the English chemist Vernon Ingram, as "a two-step process, [that] utilizes paper electrophoresis and paper chromatography. It produces splotches on paper at various locations; each mark corresponds to a peptide (two or more linked amino acids).”]

Once patterns had been prepared for several species, Pauling and Zuckerkandl compared them two at a time, and it was from the results of these comparisons that the theory of the Molecular Evolutionary Clock was developed.

Figures from: "A comparison of animal hemoglobins by tryptic peptide pattern analysis." October 1960. Proc. Natl. Acad. Sci. 46 (October 1960): 1349-1360.

The Molecular Clock differs from other evolutionary theories in that it tracks the evolution of a molecule rather than the evolution of a species. The theory states that, every so often, a mutation occurs in a given hemoglobin molecule. Generally speaking, this mutation is the source of a molecular disease, but will not cause any significant change to any organism other than its host.

Occasionally, however, a mutation will cause a lasting alteration to the molecule, and as the organism with the altered molecule reproduces, the change becomes permanent. More alterations of this nature can then occur on top of the original modification, thus resulting in even more differences in those hemoglobin molecules that have descended from the mutated original.

It is these differences that Pauling and Zuckerkandl were interested in when they compared the fingerprint patterns of different species, and their research led to an important breakthrough. As the duo compared more and more fingerprint patterns in a wider range of combinations, they observed that the number of differences between fingerprints lessened as the two species became more closely related. Pauling later stated that

[Zuckerkandl] found that in the beta chain of the human and the beta chain of the horse, for example, 20 of the 146 amino acids are different; but with human and gorilla, only one is different. It is the same amount of difference, just one amino acid residue, as between ordinary humans and sickle cell anemia patients, who manufacture sickle-cell-anemia hemoglobin.

From there Pauling and Zuckerkandl proposed that the comparative-fingerprinting method could be used to speculate as to how long ago any two species deviated from a common ancestor. Even more specifically, they reached the conclusion that one amino acid would be substituted every eleven to eighteen million years for any given species.

The evolutionary theory of the Molecular Clock was not readily accepted by scientists because it proposed a constant rate of evolution. However, it’s importance has now been noted and more research has been done on Pauling and Zuckerkandl’s original work. See, for instance, the very thorough examination conducted by Dr. Gregory J. Morgan in his 1998 paper “Emile Zuckerkandl, Linus Pauling, and the Molecular Evolutionary Clock, 1959-1965.” [pdf link], as well as Naoyuki Takahata’s “Molecular Clock: An Anti-neo-Darwinian Legacy,” [Genetics, (May 2007) 176: 1-6; not freely available online] which concludes that “a molecular clock is a most remarkable manifestation and a tribute from nature to anyone who studies evolutionary biology.”

For more information on Pauling’s hemoglobin work, please visit the website It’s in the Blood!  A Documentary History of Linus Pauling, Hemoglobin and Sickle Cell Anemia, and for more on Linus Pauling, check out the Pauling Online portal.

Pauling on the Homefront: The Development of Oxypolygelatin, Part 2

Dan Campbell and Linus Pauling in a Caltech laboratory, 1943.

“Science cannot be stopped. Man will gather knowledge no matter what the consequences — and we cannot predict what they will be. Science will go on — whether we are pessimistic, or are optimistic, as I am. I know that great, interesting, and valuable discoveries can be made and will be made…But I know also that still more interesting discoveries will be made that I have not the imagination to describe — and I am awaiting them, full of curiosity and enthusiasm.“
Linus Pauling, October 15, 1947.

After developing a promising blood plasma substitute during World War II, Pauling found his funding cut and his contract with the Office of Scientific Research and Defense coming to an end. Rather than abandon the project, the Caltech researchers chose to forge ahead.

Frustrated with the lack of progress, Pauling and his team scraped together enough residual funds to allow for one more series of experiments. Pauling began injecting mice and rabbits with his synthetic plasma, carefully monitoring their health and examining blood samples to determine the effects of the treatment. The results were satisfactory but not enough to put the project back in the good graces of the Committee on Medical Research. Pauling knew that the only way to stimulate interest (and funding) for the project was to prove that his substance could be used in humans. In September of 1944, twelve patients at Los Angeles General Hospital were injected with Oxypolygelatin, all exhibiting favorable reactions. Pauling had the results he needed.

Letter from Linus Pauling to B. O. Raulston, September 19, 1944.

Statement of Work Carried Out Under Contract OEMomr-153, 1944. Page 1.

Statement of Work Carried Out Under Contract OEMomr-153, 1944. Page 2.

In a final effort to save the project, Pauling submitted one last application, noting the success of his experiments with both animal and human patients. To aid his cause, Pauling attempted to find support at the source, sending individual letters to key members of the CMR.

In October of 1944, the CMR responded to his requests for aid, providing a $10,000, nine-month grant. The CMR had previously assured Pauling that the Committee would arrange any necessary physiological tests that could not be completed at Caltech and, upon the renewal of the Oxypolygelatin contract, they reaffirmed this promise.

While Pauling waited for the CMR to complete arrangements for testing, he and his team continued to refine the production process, ironing out wrinkles that had developed in the course of frantic experimentation. During the early months of the Oxypolygelatin program, Pauling had corresponded often with Robert Loeb, a researcher at the College of Physicians and Surgeons in New York. In a 1943 letter to Loeb he wrote,

It looks as though our method of preparation is not well enough standardized to give a uniform product – the osmotic pressure varies from preparation to preparation. With some evidence from the ultracentrifuge as to how the distribution in molecular weight is changing, we should be able to improve the method.

The lack of uniformity in the substance was a problem for Pauling and his team. In order to locate the irregularities, the researchers needed results from a series of physiological tests. Unfortunately, the CMR had yet to arrange for the promised tests and Pauling’s grant was about to expire.

Letter from Linus Pauling to Robert Loeb, August 17, 1943.

By the spring of 1945, Pauling had virtually given up on the project. He had resigned his post as responsible investigator and allowed Campbell to take his place. With the rest of Caltech still knee deep in war research, Pauling had no trouble finding other projects to attract his attention. As a result, his Oxypolygelatin work was relegated to correspondence with gelatin manufacturers and a few curious scientists. In a letter to Chester Keefer of the Committee on Medical Research, Pauling stated,

I feel that the development of Oxypolygelatin has been delayed by a full twelve months by the failure of the CMR to arrange for the physiological testing of the preparation, despite the assurances to me, beginning July 24, 1943, that this testing would be carried out under CMR arrangement. I feel that I myself am also to blame, for having continued to rely upon the CMR, long after it should have been clear to me that the promised action was not being taken and presumably would not be taken.

Letter from Linus Pauling to Chester Keefer, March 12, 1945. Page 1.

Letter from Linus Pauling to Chester Keefer, March 12, 1945. Page 2.

Letter from Linus Pauling to Chester Keefer, March 12, 1945. Page 3.

The project was dead. The CMR had lost interest and no lab in the country was either willing to or capable of performing the tests Pauling required. Even worse for the project, Germany was on the brink of surrender and Japan was losing ground in the Pacific; the war would be over soon and with victory would come the closure of war research programs all over the country.

The team quietly disbanded, each member returning to old projects or starting up fresh lines of research. In 1946, Pauling, Koepfli and Campbell filed for a patent for Oxypolygelatin and its manufacturing process which they immediately transferred to the California Institute Research Foundation.

Oxypoly-gelatin patent agreement, December 4, 1946.

In 1947, the American Association of Blood Banks was founded and in 1948 the American National Red Cross began widespread blood donation campaigns. The genesis of the two programs allowed for large supplies of fresh blood to be dispersed throughout U.S. hospitals on a regular basis, virtually eliminating the need for a plasma substitute during peacetime.

While Pauling was the source of many scientific breakthroughs during his career, in the end Oxypolygelatin was a failed project. Over the following years, he would occasionally discuss his blood plasma work with an interested scientist or mention it at a symposium address, but he never returned to the Oxypolygelatin problem.

For more information on Pauling’s Oxypolygelatin research, read his 1949 project report or view this 1974 letter regarding the development of Oxypolygelatin production in China. For additional Pauling content, visit Linus Pauling: It’s in the Blood! or the Linus Pauling Online portal.