Abstract
THE nature of the enzymes was a matter for con siderable spectlation so recently as twenty years ago, and the isolation of the gastric proteolytic enzyme pepsin by Dr. John H. Northrop in 1930 as beautiful hexagenal crystals having the composition of a protein did much to confirm their protein nature. Varous tests applied to the pure preparations showed beyond reasonable doubt that the enzymatic activity was intimately related to the protein, and subsequent work by Northrop and other workers has amply confirmed the protein nature of the soluble enzymes. In 1932, in collaboration with Dr. M. Kunitz, also of the Rockefeller Institute, he was responsible for the isolation and crystallization of trypsin, and after wards of several other proteolytic enzymes from pancreas. In the course of these studies, several inactive precursors of these enzymes were also isolated in a pure form, and it was found that trypsin and pepsin are capable of synthesizing themselves from their precursors. This autocatalytic synthesis has been compared with the multiplication of the viruses, but it has not the same specificity, as, for example, chicken pepsin is formed from chicken pepsinogen whether the reaction is catalysed by swine pepsin or chicken pepsin. It is interesting, however, that a possible inactive precursor of the tobacco mosaic virus has been reported recently. Besides his work on the isolation of the proteolytic enzymes and their precursors, Dr. Northrop has been responsible for studies on enzyme kinetics, on the estimation and purification of bacteriophage and on a large number of physico-chemical studies of which probably the best known are on the diffusion of solutes through porous membranes, on micro-cataphoresis and on the application of Gibbs's phase rule to the solubility of protein solutions as a test of their homogeneity.
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Nobel Prize for Chemistry: Dr. John H. Northrop. Nature 158, 826 (1946). https://doi.org/10.1038/158826c0
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DOI: https://doi.org/10.1038/158826c0