"Antifreeze" glycoproteins from polar fish
Antifreeze glycoproteins (AFGPs) constitute the major fraction of protein in the blood serum of Antarctic notothenioids and Arctic cod. Each AFGP consists of a varying number of repeating units of (Ala-Ala-Thr)n, with minor sequence variations, and the disaccharide β-D-galactosyl-(1→3)-α-N-acetyl-D-...
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ftanucanberra:oai:digitalcollections.anu.edu.au:1885/73535 2023-05-15T13:36:33+02:00 "Antifreeze" glycoproteins from polar fish Harding, Margaret Anderberg, Pia I Haymet, A D J 2015-12-13T22:26:30Z http://hdl.handle.net/1885/73535 unknown Blackwell Publishing Ltd 0014-2956 http://hdl.handle.net/1885/73535 European Journal of Biochemistry Keywords: alanine antifreeze protein beta dextro galactosyl (1-4) alpha n acetyl dextro galactosamine disaccharide food additive galactose glycoside hydroxyl group ice oxygen threonine unclassified drug cell membrane concentration response cryopreserv Antifreeze Fish Glycoproteins Glycosylation Hysteresis Ice/water interface Journal article 2015 ftanucanberra 2015-12-28T23:35:56Z Antifreeze glycoproteins (AFGPs) constitute the major fraction of protein in the blood serum of Antarctic notothenioids and Arctic cod. Each AFGP consists of a varying number of repeating units of (Ala-Ala-Thr)n, with minor sequence variations, and the disaccharide β-D-galactosyl-(1→3)-α-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 kinetically depressing the temperature at which ice grows in a noncolligative manner. In contrast to the more widely studied antifreeze proteins, little is known about the mechanism of ice growth inhibition by AFGPs, and there is no definitive model that explains their properties. This review summarizes the structural and physical properties of AFGPs and advances in the last decade that now provide opportunities for further research in this field. High field NMR spectroscopy and molecular dynamics studies have shown that AFGPs are largely unstructured in aqueous solution. While standard carbohydrate degradation studies confirm the requirement of some of the sugar hydroxyls for antifreeze activity, the importance of following structural elements has not been established: (a) the number of hydroxyls required, (b) the stereochemistry of the sugar hydroxyls (i.e. the requirement of galactose as the sugar), (c) the acetamido group on the first galactose sugar, (d) the stereochemistry of the β-glycosidic linkage between the two sugars and the α-glycosidic linkage to Thr, (e) the requirement of a disaccharide for activity, and (f) the Ala and Thr residues in the polypeptide backbone. The recent successful synthesis of small AFGPs using solution methods and solidphase chemistry provides the opportunity to perform key structure-activity studies that would clarify the important residues and functional groups required for activity. Genetic studies have shown that the AFGPs present in the two geographically and phylogenetically distinct Antarctic notothenioids and Arctic cod have evolved independently, in a rare example of convergent molecular evolution. The AFGPs exhibit concentration dependent thermal hysteresis with maximum hysteresis (1.2°C at 40 mg·mL-1) observed with the higher molecular mass glycoproteins. The ability to modify the rate and shape of crystal growth and protect cellular membranes during lipid-phase transitions have resulted in identification of a number of potential applications of AFGPs as food additives, and in the cryopreservation and hypothermal storage of cells and tissues. Article in Journal/Newspaper Antarc* Antarctic Arctic cod Arctic Australian National University: ANU Digital Collections Antarctic Arctic |
institution |
Open Polar |
collection |
Australian National University: ANU Digital Collections |
op_collection_id |
ftanucanberra |
language |
unknown |
topic |
Keywords: alanine antifreeze protein beta dextro galactosyl (1-4) alpha n acetyl dextro galactosamine disaccharide food additive galactose glycoside hydroxyl group ice oxygen threonine unclassified drug cell membrane concentration response cryopreserv Antifreeze Fish Glycoproteins Glycosylation Hysteresis Ice/water interface |
spellingShingle |
Keywords: alanine antifreeze protein beta dextro galactosyl (1-4) alpha n acetyl dextro galactosamine disaccharide food additive galactose glycoside hydroxyl group ice oxygen threonine unclassified drug cell membrane concentration response cryopreserv Antifreeze Fish Glycoproteins Glycosylation Hysteresis Ice/water interface Harding, Margaret Anderberg, Pia I Haymet, A D J "Antifreeze" glycoproteins from polar fish |
topic_facet |
Keywords: alanine antifreeze protein beta dextro galactosyl (1-4) alpha n acetyl dextro galactosamine disaccharide food additive galactose glycoside hydroxyl group ice oxygen threonine unclassified drug cell membrane concentration response cryopreserv Antifreeze Fish Glycoproteins Glycosylation Hysteresis Ice/water interface |
description |
Antifreeze glycoproteins (AFGPs) constitute the major fraction of protein in the blood serum of Antarctic notothenioids and Arctic cod. Each AFGP consists of a varying number of repeating units of (Ala-Ala-Thr)n, with minor sequence variations, and the disaccharide β-D-galactosyl-(1→3)-α-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 kinetically depressing the temperature at which ice grows in a noncolligative manner. In contrast to the more widely studied antifreeze proteins, little is known about the mechanism of ice growth inhibition by AFGPs, and there is no definitive model that explains their properties. This review summarizes the structural and physical properties of AFGPs and advances in the last decade that now provide opportunities for further research in this field. High field NMR spectroscopy and molecular dynamics studies have shown that AFGPs are largely unstructured in aqueous solution. While standard carbohydrate degradation studies confirm the requirement of some of the sugar hydroxyls for antifreeze activity, the importance of following structural elements has not been established: (a) the number of hydroxyls required, (b) the stereochemistry of the sugar hydroxyls (i.e. the requirement of galactose as the sugar), (c) the acetamido group on the first galactose sugar, (d) the stereochemistry of the β-glycosidic linkage between the two sugars and the α-glycosidic linkage to Thr, (e) the requirement of a disaccharide for activity, and (f) the Ala and Thr residues in the polypeptide backbone. The recent successful synthesis of small AFGPs using solution methods and solidphase chemistry provides the opportunity to perform key structure-activity studies that would clarify the important residues and functional groups required for activity. Genetic studies have shown that the AFGPs present in the two geographically and phylogenetically distinct Antarctic notothenioids and Arctic cod have evolved independently, in a rare example of convergent molecular evolution. The AFGPs exhibit concentration dependent thermal hysteresis with maximum hysteresis (1.2°C at 40 mg·mL-1) observed with the higher molecular mass glycoproteins. The ability to modify the rate and shape of crystal growth and protect cellular membranes during lipid-phase transitions have resulted in identification of a number of potential applications of AFGPs as food additives, and in the cryopreservation and hypothermal storage of cells and tissues. |
format |
Article in Journal/Newspaper |
author |
Harding, Margaret Anderberg, Pia I Haymet, A D J |
author_facet |
Harding, Margaret Anderberg, Pia I Haymet, A D J |
author_sort |
Harding, Margaret |
title |
"Antifreeze" glycoproteins from polar fish |
title_short |
"Antifreeze" glycoproteins from polar fish |
title_full |
"Antifreeze" glycoproteins from polar fish |
title_fullStr |
"Antifreeze" glycoproteins from polar fish |
title_full_unstemmed |
"Antifreeze" glycoproteins from polar fish |
title_sort |
"antifreeze" glycoproteins from polar fish |
publisher |
Blackwell Publishing Ltd |
publishDate |
2015 |
url |
http://hdl.handle.net/1885/73535 |
geographic |
Antarctic Arctic |
geographic_facet |
Antarctic Arctic |
genre |
Antarc* Antarctic Arctic cod Arctic |
genre_facet |
Antarc* Antarctic Arctic cod Arctic |
op_source |
European Journal of Biochemistry |
op_relation |
0014-2956 http://hdl.handle.net/1885/73535 |
_version_ |
1766080286355881984 |