A new method for the assay of aminoacylase: elaboration of a fixed-incubation method for routine measurements

A simple method suitable for routine determinations of aminoacylase (EC 3.5.1.14) in serum and tissue homogenates is described. It is based on the formation of red charge-transfer complexes from p-benzoquinone and amino acids liberated by cleavage of acylamino acids. Optimal substrates are trifluoroacetyl-L-methionine and chloroacetyl-L-methionine, the first being rapidly hydrolyzed by pancreatic tissue, the latter by liver and kidney homogenates. Sera preferentially split the chloroacetyl compound. Optimal conditions for the assay of serum activity are: 18-20 mm9l/l substrate concentration, 50 mmol/l phosphate buffer pH 6.0, no additives.