Correlation between changes in activity of intracellular Ca(2+)-activated proteinases and cholesterol content in mussels in response to changes in habitat saltiness was detected in mollusks from littoral and sublittoral White sea zones. Calpain activity in mussels decreased in low water saltiness and increased in high saltiness in parallel with decrease in cholesterol content, which attests to decreased microviscosity and modification of permeability of biomembranes. A complex pattern of interactions between metabolic routes in mussels under conditions of different habitat saltiness was detected.

No abstract

Seven p-nitroaniline-modified peptides were used as substrates for studies of aminopeptidase and peptidase activities in eggs of lake salmon Salmo salar Sebago at different stages of embryogenesis. The formation of p-nitroaniline during peptide hydrolysis was measured in the incubation medium and in maturing eggs. Activities of all studied aminopeptidases and peptidases increased during the development of fertilized eggs and sharply increased before hatching. L-alanin-p-NA, L-pro-p-Na, L-Arg-p-Na, and L-Phe-p-NA were hydrolyzed most of all, while N-Glt-L-Phe-p-NA and Z-Gly-Pro-p-NA least of all.