Enzymic proteolysis

Abstract

The amide group in leucinamide, asparagine and glycinamide was hydrolysed by trypsin-free erepsin, the rate of hydrolysis decreasing with the 3 substrates in the order given. Trypsin-free erepsin also hydrolysed the peptide group in chloroacetyl-asparagine, but not the amide group in either this or other asparagine-peptides examined. Pepsin, erepsin-free trypsin and papain were without action upon the amide or peptide groups in glycinamide, leucinamide, asparagine, glycylasparagine or leucyl-asparagine. Anhydroglycylasparagine (2:5-diketopiperazine acetamide) was not affected by any of the animal proteases or by papain. The bearing of these results on (i) the specificity of the proteolytic enzymes, and (ii) the "amide" nitrogen of proteins was briefly discussed.