Moses Kunitz, 1924 Courtesy of the Marine Biological Laboratory Archives Moses Kunitz (1887–1978) was a Russian-American biochemist who is best known for a series of experiments in the purification and crystallization of proteins, contributing to the determination that enzymes are proteins. He spent most of his career at Rockefeller University. Kunitz\u27s position at Rockefeller was originally secured by Jacques Loeb. After Loeb died in 1924, John H. Northrop succeeded him and retained Kunitz\u27s position; the two would collaborate extensively on experiments involving protein crystallization for much of their remaining careers. Both Northrop and Kunitz moved to Rockefeller\u27s Princeton, New Jersey campus in 1926; Kunitz returned to New ...