Peptide antifreeze

DeVries, A.L. (1983). Antifreeze peptides and glycopeptides in cold water fishes. Annual Review of Physiology 45, 245-60. 

Wang, X., A.L. DeVries, C.-H. C. Cheng (1995). Genomic basis for antifreeze peptide heterogeneity and abundance in an Antarctic eel pout Gene structures and organization. Mol. Mar. Biol. Biotech. 4 135-147. 

Rnight, C.A., Cheng, C.C., and DeVries, A.L. Adsorption of alpha-helical antifreeze peptides on specific ice crystal surface planes. Biophys. /., 59, 409,1991. 

Some solutes may cause inhibition, i.e., reduce growth at quite low concentrations. Several, generally polymeric, substances can adsorb onto ice crystals and thereby reduce the freezing rate. This includes many proteins. Especially the antifreeze peptides, found in many plants and cold-blooded animals that have been subjected to cold stress, strongly decrease growth rate at fairly low concentrations. The presence of solutes and particulate material can also affect the shape of the ice crystals. 

Mechanical damage depends on the extent of volume expansion caused by ice formation. To reduce mechanical damage, it is often desirable that ice crystals remain small small crystals may also be needed to obtain a desirable texture and mouth feel. To that end, the antifreeze peptides briefly discussed in Section 15.3.1 can be quite effective in a product like ice cream. They strongly reduce ice crystal growth at low or moderate undercooling, but they do not impede nucleation. Consequently, more, and thereby smaller, crystals will form. 

In ice cream, as well as in other frozen products, considerable recrystallization can occur, particularly when the storage temperature is relatively high and fluctuates. It involves the disappearance of small ice crystals and the growth of large ones. This suggests that the process is due to Ostwald ripening (Section 13.6), but it seems to be more complex. Gelforming biopolymers, as well as antifreeze peptides, can also retard recrystallization. 

Wilkins, S.P., Blum, A.)., Burkepile, D.E., Rutland, T.)., Wierzbicki, A., Kelly, M., Ha-mann, M.T. Isolation of an antifreeze peptide from the Antarctic sponge Homaxinella halfourensis. Cell Mol Life Sci. 2002, 59,... 

Knight s work[6]. In this case the winter flounder antifreeze peptide binds to the (201) bipyramidal plane of ice Ih along the [-112] direction, a direction whose repeat distance, 16.7 A, nearly matches that of the winter flounder polar... 

Table 1. Binding energies of winter flounder antifreeze peptide on the (201) plane of ice Ih. N+ represents the N-terminus pointing in the direction of the bipyramidal apex, while N- represents the opposite direction.

A unique family of O-linked glycoproteins permits fish to live in the icy seawater of the Arctic and Antarctic regions where water temperature may reach as low as — 1.9°C. Antifreeze glycoproteins (AFGPs) are found in the blood of nearly all Antarctic fish and at least five Arctic fish. These glycoproteins have the peptide structure... 

Separation of amino acids, peptides, and proteins Amino acids are interesting molecules by themselves from an analytical point of view for two reasons. They are inherently enantiomeric and are the building blocks of peptides and proteins. The separation of amino acids is usually done through a derivatization process due to the fact that the absorbance in the UV is low. The most frequently used derivatization is done by fluorescent tagging. Sensitivity can reach the subfemtomole level.136 139 Temperature control can be used to separate conformers.140 Two conformers of Tyr-Pro-Phe-Asp-Val-Val-Gly-NH2 and four conformers of Tyr-Pro-Phe-Gly-Tyr-Pro-Ser-NH2 were separated at subzero temperatures by including glycerol as an antifreeze component of the buffer. 

DeVries, A.L., and C.-H.C. Cheng (1992). The role of antifreeze glycopeptides and peptides in the survival of cold-water fishes. In Water and Life, pp. 301-315, ed. G.N. Somero, C.B. Osmond, and C.L. Bolis. Berlin Springer-Verlag. 

Hsaio, K.C., C.H. Cheng, I.E. Fernandes, H.W. Detrich, and A.L. DeVries (1990). An antifreeze glycopeptide gene from the Antarctic cod Notothenia coriiceps neglecta encodes a polyprotein of high peptide copy numbers. Proc. Natl. Acad. Sci. USA 94 3811-3816. 

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