Studies on the Effect of Number of Sugar Moiety in the Antifreeze Activityof Homodimeric AFGPs

Abstract

Antifreeze glycoproteins (AFGPs) are found in the plasma of deep sea polar fish such as the Antarctic nototheioids and the northern cods. The AFGPs consists of repeating tripeptides unite, Alanyl -Alanyl-Threonyl (Ala-Ala- Thr)n=4-50 unites, connected with the disaccharide β-D- galactosyl-(1→3)-α-D-N-acetylgalactosamine through a glycosidic bond at the second hydroxyl group of the threonine residue. Eight distinct AFGP subtypes exist. Among them, AFGP1 is the largest weight (33.7 kDa) and AFGP 8 is the lowest molecular weight (2.6 kDa). AFGPs are able to depress the freezing temperature of the blood serum in fish enough to keep them from freezing in their sub- zero environment while the melting temperature remains unchanged.Despite AFGPs have been consider as a potent cryopreservation, obstacle to develop AFGPs as medicinal and industrial application is mainly due to the problem of understanding how AFGPs inhibit ice crystal growth.To investigate the effect of number of hydroxyl group on antifreeze activity, we designed and synthesized the dimeric AFGP.ites, connected with the disaccharide β-D- galactosyl-(1→3)-α-D-N-acetylgalactosamine through a glycosidic bond at the second hydroxyl group of the threonine residue. Eight distinct AFGP subtypes exist. Among them, AFGP1 is the largest weight (33.7 kDa) and AFGP 8 is the lowest molecular weight (2.6 kDa). AFGPs are able to depress the freezing temperature of the blood serum in fish enough to keep them from freezing in their sub- zero environment while the melting temperature remains unchanged.Despite AFGPs have been consider as a potent cryopreservation, obstacle to develop AFGPs as medicinal and industrial application is mainly due to the problem of understanding how AFGPs inhibit ice crystal growth.To investigate the effect of number of hydroxyl group on antifreeze activity, we designed and synthesized the dimeric AFGP.