ANTIFREEZE GLYCOPEPTIDES OF THE HIGH-ANTARCTIC SILVERFISH PLEURAGRAMMA ANTARCTICUM (NOTOTHENIOIDEI)

Antifreeze glycopeptides (AFGP) have been isolated from the fully pela gic high-Antarctic silverfish Pleuragramma antarcticum of the suborder Notothenioidei (Perciformes). The fishes were caught during the PRV P olarstern expedition EPOS III (Jan-Mar, 1989) in the eastern and south eastern Weddell Sea. Glycoconjugate and amino acid analysis of antifre eze glycopeptides (AFGP) indicate that the glycopeptide structure is i dentical to the polymers of H2N[Ala-Ala(beta-galactosyl(1 -->3)- alpha -N-acetylgalactosamine)Thr](n)Ala-Ala-COOH of previously studied Antar ctic notothenioids. The content of AFGPs in P. antarcticum is lower th an in other notothenioid fish from the same region. Antifreeze activit y shows a maximal hysteresis of 1.19 degrees C at a concentration of 2 0 mg/ml AFGP. A linear increase in activity of the antifreeze glycopep tides could be demonstrated concomittant with a decreasing ice content . The freezing point of blood serum is -1.9 degrees C.