Dynamics of activity of intracellular cysteine-dependent proteases and some peptidases in embryogenesis of Atlantic salmon Salmo salar L.

The dynamics of the activity of cysteine-dependent enzymes involved in intracellular proteolysis was studied in freshwater salmon Salmo salar L. during its early development: in the period from the blastodisc formation to hatching and in eggs before fertilization. The Ca²⁺-activated proteolytic activity of calpains, the activity of acidic lysosomal protease cathepsin B, and the activity of several peptidases that use the chromogenic component p-nitroaniline-containing peptides (L-Ala-pNA, L-Pro-pNA, L-Arg-pNA, N-Bzl-L-Arg-pNA, L-Phe-pNA, N-Glu-L-Phe-pNA, and Z-Gly-Pro-pNA) as substrates were analyzed. It is shown that the activity of the enzymes of interest increases at the stage of late blastula and early gastrula. The next increase in the activity of cathepsin B and calpain is observed at the stage of eye pigmentation, and the activity of peptidases and cathepsin B increases in eggs before hatching. The functional role of changes in intracellular proteolytic enzymes in the processes of protein metabolism associated with the Atlantic salmon embryo is discussed.