ANTIFREEZE GLYCOPEPTIDES AND PEPTIDES IN ANTARCTIC FISH SPECIES FROM THE WEDDELL-SEA AND THE LAZAREV-SEA

Antifreeze glycopeptides and peptides have been isolated from 37 speci es of Antarctic fish representing the families Nototheniidae, Artedidr aconidae, Bathydraconidae, Channichthyidae, Muraenolepididae, Liparidi dae, Zoarcidae and Myctophidae. Amino acid and carbohydrate analysis a s well as antifreeze activity indicate that all investigated nototheni oids contain antifreeze glycopeptides (AFGP). Pleuragramma antarcticum , Lepidonotothen kempi, Bathydraco marri and Dolloidraco longedorsalis synthesize additional antifreeze molecules. The non-notothenioid spec ies possess antifreeze peptides (AFP), except Muraenolepis marmoratus and Macrourus holotrachys, which possess a glycosylated antifreeze pep tide similar to the AFGP found in the notothenioid species. A novel gl ycopeptide comprised of the carbohydrate residue N-acetylglucosamine a nd the amino acids asparagine, glutamine, glycine, alanine, and traces of arginine, valine, leucine and threonine was isolated and character ized from P. antarcticum. The level of antifreeze concentration was de pendent on the ambient water temperature, the depth of catch and life cycle of the species. Antifreeze activity of AFGP varies between 0.52 (Neopagetopsis ionah) and 1.20 degrees C (P. antarcticum) at a concent ration of 20 mg ml(-1) Antifreeze activity of AFP is lower than 0.50 d egrees C. A linear increase in activity of the AFGP could be demonstra ted concomitant with decreasing ice content. The structural diversity of antifreeze molecules and their occurrence in a wide range of Arctic and Antarctic fish species suggest that they evolved from precursor p roteins before the continental drift and recently during Cenozoic glac iation into the various antifreeze molecules.