Various peptides as substrates for aminopeptidases from salmon eggs during embryogenesis

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.