He discovered that enzymes can be crystallized, for which he shared the Nobel Prize in Chemistry in 1946 with John Howard Northrop and Wendell Meredith Stanley.

[4] While hunting at age 17, Sumner was accidentally shot by a companion and as a result his left arm had to be amputated just below the elbow.

[5] Sumner graduated from Harvard University with a bachelor's degree in 1910[4] where he was acquainted with prominent chemists Roger Adams, Farrington Daniels, Frank C. Whitmore, James Bryant Conant and Charles Loring Jackson.

[citation needed] After a short period of working in the cotton knitting factory owned by his uncle, he accepted a teaching position at Mount Allison University in Sackville, New Brunswick, Canada.

[4] It was in 1917 at Cornell where Sumner began his research into isolating enzymes in pure form; a feat which had never been achieved before.

Sumner's work was unsuccessful for many years and many of his colleagues were doubtful, believing that what he was trying to achieve was impossible, but in 1926 he demonstrated that urease could be isolated and crystallized.

By this time, John Howard Northrop of the Rockefeller Institute had obtained other crystalline enzymes by similar methods, starting with pepsin in 1929.