Features of the organization of low-molecular weight proteins from the blood and tissue fluid of the common stingray Dasyatis pastinaca (Chondroichthyes: Trygonidae)

Abstract

Low-molecular weight proteins were revealed in the blood serum and tissue fluid from the muscles of the common stingray Dasyatis pastinaca. In the absence of urea in the reaction medium in vitro, these proteins aggregated into supramolecular complexes; 8 M urea caused the disintegration of these complexes into individual proteins. The role of urea as a component of an organism’s fluids in the formation of the structural arrangements of blood plasma proteins and other biological fluids of cartilaginous fishes is discussed. It is shown that the extracellular fluids of the stingray also contain low-molecular weight proteins as osmotically active compounds, along with urea, trimetilaminoxid, and salts.