Antifreeze Glycopeptides of Antarctic Fish: Comparative Aspects of Their Biochemistry and Physiology

• Main Author: Ahlgren, Jeffrey Allen
• Format: Text
• Language: unknown
• Published: 1987
• Subjects: Chemistry; Biochemistry; Antarctic; The Antarctic; Antarc*
• Online Access: http://hdl.handle.net/2142/77684

124 p. Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1987. The presence of antifreeze glycopeptides (AFGPs) in the blood of polar fishes allows fish to live in ice-laden seawater at a temperature below what colligative properties would dicate to be the freezing point of their blood. AFGPs are well-characterized from two antarctic species, Pagothenia borchgrevinki and Dissostichus mawsoni. Eight other species of antarctic fish were examined for AFGPs, and results showed a high degree of similarity of AFGP between species. ('3)H AFGP was prepared and injected in the blood of the antarctic nototheniid fish Trematomus bernacchii, and the results showed that body fluids which are blood filtrates, including the interstitial fluid of all tissues except brain, contain all AFGPs, while fluids formed by secretory processes lack AFGP and are supercooled at environmental temperatures (-1.9(DEGREES)C). Skin from the antarctic fish Gymnodraco acuticepts was shown to prevent ice propagation into supercooled saline at environmental temperatures, demonstrating the role of extracellular AFGP in the prevention of ice propagation. The amino acid proline, which is present in the peptide portion of all low molecular weight AFGPs examined to date, was shown to enhance the rate of glycosylation by 10-fold of deglycosylated low molecular weight AFGP in vitro by comparing the rates of glycosylation of proline-containing and proline-free low molecular weight deglycosylated AFGP.