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Edwin Cohn Edwin Cohn

Born: December 17, 1892 in New York
Died: October 1, 1953
Nationality: American
Occupation: biochemist

Cohn, Edwin Joseph (Dec. 17, 1892 - Oct. 1, 1953), biochemist and protein chemist, was born in New York City, the son of Abraham and Maimie Einstein Cohn. His father was a highly successful tobacco merchant who owned extensive plantations in southwestern Georgia but spent most of his time in New York City. The family traveled often, enjoyed literature and the arts, and cultivated intellectual interests.

In his first years as an undergraduate at Amherst College, Cohn devoted himself to art and literature. In his third year, however, he decided on a scientific career. Advised by his elder brother Alfred and by Jacques Loeb, he transferred to the University of Chicago, where he studied chemistry under Julius Stieglitz and physics under R. A. Millikan. He received the B.S. degree in 1914 and the Ph.D. in 1917. His research, much of which was done at Woods Hole, Mass., was on the physiology of spermatozoa, with Frank R. Lillie, and on the physical chemistry of seawater, with Lawrence J. Henderson.

During this period Cohn made the crucial decision to devote his scientific life to the study of proteins. This led him to collaborate with Thomas B. Osborne at the Connecticut Agricultural Experiment Station in New Haven, but the entry of the United States into World War I interrupted this work. Cohn returned to Harvard, where he joined Henderson in a study of the physical chemistry of making bread from potatoes and other nongrain sources, a problem of pressing interest in wartime.

In 1917 Cohn married Marianne Brettauer, who played an important part in his professional as well as his personal life. She studied biological chemistry, assisted in the laboratory, and was his first secretary. Her understanding, tact, and devotion served to restrain and balance his intense, impulsive, and sometimes explosive nature. They had two sons.

With the end of the war, the Cohns made a long visit to South America. On their return Cohn received one of the first National Research Council fellowships. From September 1919 to March 1920, he worked in Copenhagen with the great Danish protein chemist S. P. L. Sorensen, an experience critical to his future career, and also worked at the University of Cambridge.

In 1920 Henderson invited Cohn to join him in the newly established department of physical chemistry at Harvard Medical School. Henderson, the official head, soon left the actual running of the department to Cohn, who became chairman some years later. Cohn developed an extremely active program of research in protein chemistry, with emphasis on the solubility of proteins in various media, on their sizes and shapes, and on their molecular electric charges under various conditions.

Cohn's approach was deeply influenced by his close association with George Scatchard, who became professor of physical chemistry at Massachusetts Institute of Technology. A master of fundamental physical chemistry, Scatchard also developed an abiding interest in the large protein molecules that Cohn was studying. They remained close until Cohn's death.

Cohn worked for several years to purify the substance in liver that George R. Minot and W. P. Murphy had shown to cure pernicious anemia. He obtained a concentrated liver extract of great clinical value, but never succeeded in obtaining the essential substance in pure form. (This substance, vitamin B-12, was isolated by other workers in 1948.)

About 1930 Cohn alarmed his physicians by developing high blood pressure. They urged him, in vain, to reduce his strenuous activities and to lead a quieter life. He was passionately involved in his research and intensely ambitious; also, he was driven to overcome the significant social and professional obstacle that his Jewishness then represented. At the same time, Cohn could be genial and relaxed; and he keenly enjoyed and appreciated art, literature, and travel.

For some ten years after 1930, Cohn centered his research on amino acids and peptides, the smaller units of which the protein molecules are composed. These small molecules, of known chemical structure, could be studied by the same techniques employed for the highly complicated proteins; and the data could be interpreted with far more assurance. Amino acids and peptides, like proteins, contain positive and negative electric charges and many other groups, both polar and nonpolar. The aim of the research was to correlate structures with a wide range of physical properties and to interpret the data in terms of basic principles. Cohn showed a remarkable talent for bringing together a group of investigators and inspiring them to cooperative undertakings.

Cohn returned to the study of proteins around 1938. Then war in Europe, and the increasing imminence of American involvement, led him to concentrate on the separation of the many different proteins of blood plasma, for which there was urgent need in wartime medicine and surgery. Cohn envisaged a comprehensive process for this separation, with each protein to be available in concentrated form. With support from the Committee on Medical Research, the number of biochemists in the project grew rapidly. They worked in close cooperation with numerous clinicians who tested the proteins separated in the laboratory. The basis of the chemical procedure was the differential precipitation of the plasma proteins with ethyl alcohol at low temperature, with careful control of salt concentration, temperature, and acidity or alkalinity of the medium.

The most urgently needed plasma protein was serum albumin, for transfusion in treatment of shock; useful albumin preparations were obtained by 1942. The methods developed in Cohn's laboratory were widely applied by commercial firms that altogether produced more than two million units of albumin for transfusion before the war ended. Gamma globulin, used for passive immunization against measles and hepatitis, and fibrin foam and film, for neurosurgery, were other products that were widely used. Many other plasma constituents were studied and provided information of great scientific value.

Marianne Cohn died early in 1948, and in June of that year Cohn married Rebekah Higginson, a striking embodiment of his increasing ambition to be accepted into old Boston society. In 1949 he became Higgins University professor, and the department acquired special status as a university laboratory. He continued to develop new techniques for fractionating blood plasma, for preserving red cells for transfusion, and for studying other constituents of blood. The stress of his life, and the high blood pressure from which he had suffered for more than twenty years, seriously affected his health; and he died in Boston, Mass., of a stroke.

A man of great intensity, Cohn was always forceful and often dominating. He was widely regarded as difficult and made many enemies. Nevertheless, he attracted a great variety of able younger workers, showed insight in judging their particular abilities, and generally gave them freedom to develop. His influence has persisted, not only through the work of his students but also in the activities of the Protein Foundation -- now called the Center for Blood Research -- which he established in the last year of his life.

-- John T. Edsall

Further Readings

[Most of Cohn's correspondence and unpublished papers seem to have disappeared. A few papers are in the Countway Library at Harvard Medical School. The most extensive biographical article is J. T. Edsall, BIOGRAPHICAL MEMOIRS. National Academy of Sciences (1961), with portrait and bibliography. An earlier article by Edsall, in ERGEBNISSE DER PHYSIOLOGIE, BIOLOGISCHE CHEMIE, UND EXPERIMENTELLEN PHARMAKOLOGIE (1955) -- in English, with photograph -- gives a briefer biography but a more extensive bibliography, including many papers by Cohn's students. Also see DICTIONARY OF SCIENTIFIC BIOGRAPHY, III. For a revealing view of Cohn by an intimate friend and colleague, see G. Scatchard's Edwin J. Cohn lecture: "Edwin J. Cohn and Protein Chemistry," VOX SANGUINIS, Jan. 1969. John T. Edsall, UNIVERSITY LABORATORY OF PHYSICAL CHEMISTRY RELATED TO MEDICINE AND PUBLIC HEALTH, Harvard University (1950), contains a history of the department of physical chemistry, 1920; a shorter version is in AMERICAN SCIENTIST, Autumn 1950. E. J. Cohn and J. T. Edsall, PROTEINS, AMINO ACIDS AND PEPTIDES (1943; reiss. 1965), includes much of the work of the laboratory in the period up to 1940. For the work done in the war and immediately thereafter, see Cohn's "The History of Plasma Fractionation," in ADVANCES IN MILITARY MEDICINE, I (1948), pp. 364-443.]

Photo: Courtesy of the National Library of Medicine.

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Source: From DICTIONARY OF AMERICAN BIOGRAPHY, Supplement 5: 1951-1955. American Council of Learned Societies, 1977. Reprinted by permission of the American Council of Learned Societies.


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