[Co-precipitation of pepsin with products from the enzymatic synthesis of peptides as a factor limiting the effectiveness of the enzyme].

Porcine pepsin behaviour during the synthesis of peptide p-nitroanilides and esters has been studied. In many cases, especially when long-chain peptides, such as Z-Ala-Ala-Phe-Leu-Ala-Ala-OMe, were synthesized, pepsin disappeared from the solution, being entrapped by the product precipitate rather than inactivated. Sorption of the enzyme on the product might be partially responsible for this effect. The active enzyme could be eluted from the precipitate by NaCl and isopropanol. Non-proteolytic proteins (lysozyme, bovine albumin, carbonic anhydrase) could also co-precipitate with pepsin.