Antifreeze glycoproteins (AFGPs) constitute the major fraction of protein in the blood serum of Antarctic noto-thenioids and Arctic cod. Each AFGP consists of a varying number of repeating units of (Ala-Ala-Thr)n, withminor sequence variations, and the disaccharide b-D-galactosyl-(1fi3)-a-N-acetyl-D-galactosamine joined as a glycoside to the hydroxyl oxygen of the Thr residues. These compounds allow the fish to survive in subzero ice-laden polar oceans by kineticallydepressing the temperatureatwhich icegrows ina noncolligative manner
