The Characterization of Proteolytic Enzymes with Synthetic Poly-alpha-amino Acids.

Abstract

Polyamino acids with very high molecular weight (> 150,000) were found to be well suited for rapid viscosimetrical determinations. The 2 water soluble polyamino acids, poly-L-lysine and poly-L-glutamic acid, were suitable substrates for trypsin, ficin, Aspergillus [fumigatus] proteinase, and Paracentrotus [lividusl egg cathepsin D 2. On the other hand these substrates were not hydrolyzed by pepsin [human], thyroid proteinases, or cathepsin D 1. Aspergillus proteinase hydrolyzed both substrates optimally in the pH interval 4.6-5.3. Cathepsin D 2 had pH optimum for poly-L- lysine at 4.5-4.8 and for poly-L-glutamic acid at 4.4-4.5. Judging from the gel filtration patterns of hydrolysis trypsin and crude ficin randomly degraded the substrate into products of varying magnitude whereas cathepsin D 2 split the substrate into products of a determined pattern. Purified ficin and Aspergillus extract acted primarily as exopeptidases giving low molecular components. In presence of poly-D-glutamic acid which was not hydrolyzed by cathepsin D 2, the hydrolysis of poly-L-glutamic acid was reduced by 75% at the optimal pH 4.45.