Regulations of enzymes in animals: effects of developmental processes, cancer and radiation. Progress report IX, 1 May 1974--31 April 1975

Investigations of the properties of variant forms of emnzymes in rat tissues were continued. Two glutamyltransferases, one which remains associated with glutamine synthetase and the other which can be separated from it, were purified. A new assay method forglutaminase activity was established which facilitated further characterization of the 3 isozymes and their concentration in normal and neoplastic tissues. Studies of arginase led to the demonstration of the role that the new variant of arginase plays in proline synthesis in mammary gland. An inhibitor of asparagine synthetase, which is absent from fetal liver and tumors, was discovered in adult rat liver. Peptidyl proline hydroxylase (an essential enzyme in collagen synthesis) was identified as one of the most sensitive indicators of neoplastic growth. The spectrum of experimental, transplantable rat tumors was extended to a series of salivary gland tumors and a radiation-induced lymphoma. (U.S.)