James Sumner received the Nobel Prize in chemistry in 1946 (which he shared with John Northrop and Wendell Stanley), "for his discovery that enzymes can be crystallized." In asserting that enzymes were proteins, Sumner had to battle the considerable opposition of European chemists for many years, particularly that of Richard Willstätter's group in Munich, who believed that enzymes belonged to an as yet unknown class of chemical compounds.
Sumner wrote in his Nobel Lecture: "I decided in 1917 to attempt to isolate an enzyme…. I desired to accomplish something of real importance. In other words I decided to take a 'long shot.' … Since the jack bean Canavalia ensiformis appeared to be extraordinarily rich in urease, I could see no reason why this enzyme could not be isolated in pure form and characterized chemically." The task took nine years.
Sumner's earliest research facilities were primitive. His laboratory did not even possess an ice chest. He noted, also in his Nobel Lecture: "I would leave cylinders of 30 percent alcoholic extracts on window ledges and pray for cold weather." (He frequently became discouraged.)
Treatment of the jack bean meal with 30 percent alcohol dissolved most of its urease but failed to dissolve other proteins, hence he achieved a considerable purification. Sometime in 1926, it occurred to him that he might achieve even greater purification by using dilute acetone instead of alcohol. A filtered acetone extract, chilled overnight, contained no visible precipitate. However, there was precipitate. In Sumner's own words: "Upon observing a drop of the liquid under the microscope it was seen to contain many tiny crystals…. I centrifuged off some of the crystals and observedthat they dissolved readily in water. I then tested this water solution. It gave tests for protein and possessed a very high urease activity. I then telephoned to my wife, 'I have crystallized the first enzyme.'"
Willstätter and his collaborators challenged Sumner's claim that urease was a pure protein. After 1926 Sumner and collaborators provided further evidence that urease was indeed a protein molecule and that Willstätter's objections were based on incorrect experimentation. In 1930 Northrop had shown that pepsin was a protein, and in 1937 Sumner isolated catalase in pure crystalline condition. Sumner's initially controversial claims were thus fully vindicated.
James Batcheller Sumner was born in Canton, Massachusetts, in 1887. As a young man of seventeen he suffered a tragic misfortune. While he was out hunting with a companion, the companion accidentally shot him in the left arm, which had to be amputated above the elbow. (Sumner was left-handed.) With amazing courage and determination he taught himself to get along with one arm, and to use his right in activities for which he had previously used only his left. He continued on as a keen sportsman and, despite his disability, came to excel in tennis.
In 1906 Sumner entered Harvard College, graduating in 1910 with a degree in chemistry. He earned a Ph.D. in biological chemistry in 1914 for research carried out under Otto Folin on the formation of urea in animals. When Sumner first applied to do graduate work, Folin suggested he take up law, as he would never be able to carry out laboratory assignments as a one-armed man. Thus challenged, Sumner went on to show how skilled an experimentalist he could become.
In 1914 Sumner became an assistant professor of biochemistry at the Ithaca division of the Cornell University Medical College and was promoted to full professor in 1919. In 1938 he moved to the Cornell School of Agriculture, where in 1947 a laboratory of enzyme chemistry was established under his direction. Active to the last, he died in 1955 of cancer, aged sixty-seven.
see also Proteins; WillstÖtter, Richard.
Keith L. Manchester
Sumner, James (1937). "The Story of Urease." Journal of Chemical Education 14: 255–259.
Sumner, James (1946). "The Chemical Nature of Enzymes." Nobel Lecture, presented in November 1946. In Nobel Lectures: Chemistry. New York: Elsevier.
Sumner, James. Nobel Lecture. Available from <http://www.nobel.se/chemistry/laureates>.