Edwin J. Cohn

Edwin Joseph Cohn (1892-1953) was an early protein scientist. He made important advances in the physical chemistry of proteins, and was responsible for the blood fractionation project that saved thousands of lives in World War II.

Blood fractionation project

Cohn became famous for his work on blood fractionation during World War II.

Fred S. Cohen still has Cohn's office blackboard, on which is inscribed a quotation from Goethe's Faust: "Das Blut ist ein ganz besonderer Saft." (Blood is a very special liquid.) (This was reported in the 13 July 2003 issue of the New England Journal of Medicine.)

Physical chemistry of proteins

Cohn is also well-remembered for his studies of the physical chemistry of proteins, particularly his general "salting out" equation for protein solubility (1925)

$\log K_{p}=-\alpha _{S}[S]+\beta _{S}$

where $K_{p}$ is the protein solubility constant and $\alpha _{S}$ and $\beta _{S}$ are constants characteristic of the particular ion S whose concentration (or, more correctly, activity is [S].

Cohn was a long-time collaborator and friend of another important physical chemist, George Scatchard.

A most important book

In 1943, Edwin Cohn and John Edsall published Proteins, Peptides and Amino Acids, a book that summarized the known physical chemistry of proteins and deeply influenced succeeding generations of protein scientists.

Personality

Edwin Cohn was an excellent project leader, being driven, ambitious, and extremely well-organized. He also had a keen taste in people and scientific projects and could sense when either would be successful. The success of the blood fractionation project was due in great part to his management, and he can be considered responsible for saving thousands of lives.

Cohn was also selfless in the best (and worst) scientific tradition. For example, he would often give public demonstrations of the blood fractionation machine, in which he would fractionate his own blood on the stage during the lecture. In one such lecture, the machine became blocked (without Cohn's knowledge) and exploded, showering the first few rows of the audience with Cohn's blood. Cohn maintained his sang froid, however, and continued his lecture without significant interruption. More generally, Cohn drove himself relentlessly and ignored his doctors' advice to cut back on working because of his high blood pressure (which finally killed him).

However, Cohn was also well-known for being harsh and demanding of his subordinates, of being a martinet.

Historical dates

Edwin J. Cohn was born on 17 December 1892 in New York City to Abraham and Maimie Einstein Cohn.

Cohn died on 1 October 1953 in Boston, of a stroke brought on by hypertension caused by an undiagnosed pheochromocytoma.

References

• Cohn EJ. (1925) "The Physical Chemistry of the Proteins",

Physiol. Rev., 5, 349-437.

• Surgenor DM (2002) Edwin Cohn and the Development of Protein Chemistry,

Center for Blood Research and Harvard Medical School.

External links

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