The Nobel Prize-winning American biological chemist John Howard Northrop (1891-1987) established that enzymes are proteins and also showed that a bacterial virus is a nucleic acid-protein complex.

On July 5, 1891, J. H. Northrop was born in Yonkers, NY. He attended Columbia University, majoring in chemistry and earning a bachelor of science degree in 1912 and a masters degree in science in 1913. He studied the nature of phosphorus in starch for his thesis research and received a doctoral degree in chemistry in 1915. Northrop accepted a position with the biologist Jacques Loeb at the Rockefeller Institute for Medical Research in New York City.

Early Research

In his early career, Northrop was concerned with the effect of environmental factors on the hereditary properties of fruit flies (Drosophila). He began by growing the flies aseptically, without pathological microorganisms. It was probably the first time animals had been cultivated free of microorganisms. Northrop found that...