L-Glutamic acid γ-p-nitroanilide (γ-Glu-pNA) is a colorimetric substrate for γ-glutamyl transpeptidase.1,2 Upon enzymatic cleavage, pNA is released which can be quantified by colorimetric detection at 405 nm as a measure of γ-glutamyl transpeptidase activity.
1.Griffith, O.W., and Tate, S.S.The apparent glutathione oxidase activity of γ-glutamyl transpeptidase. Chemical mechanismJ. Biol. Chem.255(11)5011-5014(1980) 2.King, J.B., West, M.B., Cook, P.F., et al.A novel, species-specific class of uncompetitive inhibitors of γ-glutamyl transpeptidaseJ. Biol. Chem.284(14)9059-9065(2009)