Acetyl-L-alanyl-L-alanyl-L-alanine methyl ester: a new highly specific elastase substrate

Abstract

Acetyl-L-alanyl-L-alanyl-L-alanine methyl ester is a highly specific esteratic substrate for elastase. It is only slowly hydrolyzed by trypsin and α-chymotrypsin (0.13 and 1.2%, respectively, of the rate of elastase), and can be used in crude preparations and for the study of proelastase activation. At pH 8.0 and 25°, KM = 0.43 mM; kcat = 73 s−1 and is independent of pH between 7.5 and 10.5. Acetyl-L-alanine methyl ester is a poor substrate with KM 153 mM and kcat 6.7 s−1.