Edwin Joseph Cohn

Blood fractionation project

Cohn became famous for his work on blood fractionation during World War II. In particular, he worked out the techniques for isolating the serum albumin fraction of blood plasma, which is essential for maintaining the osmotic pressure in the blood vessels, preventing their collapse. Transfusions with purified albumin on the battlefield rescued thousands of soldiers from shock.

After the war, Cohn worked to develop systems by which every component of donated blood would be used, so that nothing would be wasted.

On Cohn's office blackboard was inscribed a quotation from Goethe's Faust: "Das Blut ist ein ganz besonderer Saft." (Blood is a very special juice.)

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)

where is the protein solubility constant and and are constants characteristic of the particular ion S whose concentration (or, more correctly, activity) is . This equation is identical to the Setschenow solubility equation.

In 1943, Cohn and John Edsall published Proteins, Amino Acids and Peptides, a book that summarized the known physical chemistry of proteins and deeply influenced succeeding generations of protein scientists. Cohn was a long-time collaborator and friend of another important physical chemist, George Scatchard.

Personality

Cohn was elected to the American Academy of Arts and Sciences in 1926, the United States National Academy of Sciences in 1943, and the American Philosophical Society in 1949.

He would often give public demonstrations of the blood fractionation machine, in which he would fractionate his own blood on stage during the lecture. In one such lecture, at the Instituto Superior Técnico in Lisbon, 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 composure, however, and continued his lecture without significant interruption.

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