348-67-4

1509-92-8

348-67-4

The general procedure for the determination of N-d-AAase activity using N-acetyl-D-methionine as substrate was as follows: first, N-d-AAase was incubated with N-acetyl-D-methionine at 4°C. Subsequently, a colorimetric solution mixture containing d-amino acid oxidase (coupled with horseradish peroxidase), peroxidase (10 U/mL), 4-aminoantipyrine (0.04 mg/mL) and phenol (0.8 mM) was added. Absorbance (OD) was measured at 520 nm. The unit of enzyme activity was defined as the amount of catalytic production of 1 μmol D-methionine per minute. Protein concentration was determined by the Bradford method using bovine serum albumin as standard [32]. The kinetic parameters kcat and Km were determined by fitting the initial rate as a function of substrate concentration to the Michaelis-Menten equation.