Effect of some acyl derivatives of amino acids on cell-free protein synthesizing systems from Ehrlich ascites, rat and mouse liver cells

Abstract

Intraperitoneal injections of carbobenzoxy (CBZ)phenylacetyl and phenylpropionyl derivatives of ammo acids, especially derivatives with more than one aromatic group, were found to markedly inhibit the growth of Ehrlich ascites tumor in mice [l-3] .I Such derivatives also strongly inhibit a number of isolated enzyme systems (rat liver asparaginase and glutaminase [4,5] , rat liver and ovine brain glutamine synthetase [6,7] , rat liver NAD-synthetase [8] and the purine synthesizing system of pigeon and chicken liver [9]. Preliminary experiments with suspensions of Ehrlich ascites cells carried out in this department by G. Mor also revealed that ol,e-di-CBZL-lysine and N-CBZ-S-benzyl-L-cysteine markedly inhibit the incorporation of L-leucine and L-phenylalanine into ascites protein. The latter finding, however, does not necessarily indicate that these compounds inhibit the protein synthesis as such (e.g., they might affect some ATP generating enzyme systems). We decided therefore to investigate the effect of the above amino acid derivatives on cell-free protein synthesizing systems prepared from Ehrlich ascites cells and from rat and mouse liver. The present paper deals with this subject.