Born July 5, 1891, in Yon-kers, N. Y. American biochemist.

In 1912, Northrop graduated from Columbia University, where he received the Ph.D. degree in 1915. From 1915 to 1962 he worked at the Rockefeller Institute for Medical Research. His main works deal with the biochemistry of enzymes. Together with his co-workers, he was the first to isolate proteolytic enzymes in crystalline form, including pepsin (1930) and trypsin (1932). He was also the first to isolate a bacteria virus and diphtheria antitoxin. Following up the work of J. B. Sumner, he showed that enzymes are proteins. Northrop won a Nobel Prize in 1946, together with W. M. Stanley and J. B. Sumner.