Isolation of anthglutin, an inhibitor of γ-glutamyl transpeptidase from Penicillum oxalicum

Abstract Anthglutin, a new inhibitor of γ-glutamyl transpeptidase, has been isolated from the cultured medium of Penicillium oxalicum and its structure established as l-γ- l -glutamyl-2-(2-carboxyphenyl)hydrazine. The isolation of anthglutin was achieved by ion-exchange chromatography. Anthglutin inhibited γ-glutamyl transpeptidase specifically and the kinetic analysis of the inhibition showed that anthglutin inhibited the enzyme competitively with regard to the glutamyl donor, γ-glutamyl- p -nitroanilide, and noncompetitively with regard to the glutamyl acceptor, glycylglycine. K 1 values were 5.7 μ m for the hog kidney enzyme, 18.3 μ m for the human kidney enzyme, 13.6 μ m for the human liver soluble enzyme, and 10.2 μ m for the bound enzyme. After oral administration of [ 14 C]methionine and anthglutin to rats, no effect of anthglutin was observed on the absorption of methionine in the intestine.