Kinetic studies were made of the hydrolysis by trypsin of alpha-N-acetylglycyl-L-lysine methyl ester and of its neutral analogue alpha-N-acetylglycyl-epsilon-N-formyl-L-lysine methyl ester. The latter substance is a moderately good substrate for trypsin, and this observation is discussed in terms of the substrate specifically of the enzyme. The actions of trypsin and of the lysine-specific proteinase from Armillaria mellea on both a native and a formylated polypeptide substrate were compared. Both enzymes were found to hydrolyse specifically bonds to epsilon-N-formyl-lysine in the formylated substrate.
