Antifreeze glycopeptides of antarctic fishes

A method is described for analysis of amino acid composition and concentration of antifreeze glycopeptides of Antarctic fish by automatic amino acid analysis of hydrolyzed samples purified by trichloroacetic acid fractionation. Preparations were 98% pure and showed characteristic alanine, threonine and proline compositions. Analyses were carried out in 17 known species of Ross Sea, Antarctica, fishes and in 11 undescribed species tentatively placed in genera, where possible, or families. Collections have been preserved for classification. The results provide evidence of species specificity in amino acid composition and plasma concentration of these substances. Closely related species showed nearly identical Pro/Ala ratios, but differing concentrations. The results do not support reclassification of Trematomus and Notothenia into a single genus or the inclusion of the genus Pleuragramma in the family Nototheniidae. Data obtained for developing ovaries of 6 species showed concentrations of these substances (per unit wet wt) about one-half those of plasma and similar, but not identical, amino acid compositions to those of plasma. The total amount in eggs was 4 times that of plasma in pre-spawning individuals. Calculations are presented to indicate the role of these substances in the protein metabolic economy of the animal for Nototheniidae and Channichthyidae.