Antitumor activities of bacterial leucine dehydrogenase and glutaminase a

Abstract

Current observations on the inhibition of tumor growth by enzymes such as asparaginase [ 1,2], glutaminase [3] , arginase [4,5] and phenylalanine ammonia-lyase [6] , which catalyze the essentially irreversible degradation of amino acids, have stimulated the search for the antineoplastic activity of other microbial enzymes related to amino acid metabolism. The antitumor activities of a folate-cleaving bacterial enzyme, carboxypeptidase G, [7,8], and jack bean urease [9] , and the inhibition ofgrowth and DNA synthesis of tumor cells by ascorbic acid oxidase [lo] also have been recently reported. In the present communication we describe some studies on the antitumor activities of several bacterial enzymes, especially leucine dehydrogenase and isozyme A of glutaminase, which catalyze the reversible oxidative deamination of L-leucine and some other aliphatic amino acids in the presence of NAD [ 1 l] , and the deamidation of glutamine and asparagine [ 121, respectively.