Animal ice-binding (antifreeze) proteins and glycolipids: an overview with emphasis on physiological function

Abstract

Ice-binding proteins (IBPs) assist in subzero tolerance of multiple cold-tolerant organisms: animals, plants, fungi, bacteria etc. IBPs include: (1) antifreeze proteins (AFPs) with high thermal hysteresis antifreeze activity; (2) low thermal hysteresis IBPs; and (3) icenucleating proteins (INPs). Several structurally different IBPs have evolved, even within related taxa. Proteins that produce thermal hysteresis inhibit freezing by a non-colligative mechanism, whereby they adsorb onto ice crystals or ice-nucleating surfaces and prevent further growth. This lowers the so-called hysteretic freezing point below the normal equilibrium freezing/melting point, producing a difference between the two, termed thermal hysteresis. True AFPs with high thermal hysteresis are found in freeze-avoiding animals (those that must prevent freezing, as they die if frozen) especially marine fish, insects and other terrestrial arthropods where they function to prevent freezing at temperatures below those commonly experienced by the organism. Low thermal hysteresis IBPs are found in freeze-tolerant organisms (those able to survive extracellular freezing), and function to inhibit recrystallization -a potentially damaging process whereby larger ice crystals grow at the expense of smaller ones -and in some cases, prevent lethal propagation of extracellular ice into the cytoplasm. Ice-nucleator proteins inhibit supercooling and induce freezing in the extracellular fluid at high subzero temperatures in many freeze-tolerant species, thereby allowing them to control the location and temperature of ice nucleation, and the rate of ice growth. Numerous nuances to these functions have evolved. Antifreeze glycolipids with significant thermal hysteresis activity were recently identified in insects, frogs and plants.

Antifreeze proteins govern the precipitation of trehalose in a freezing-avoiding insect at low temperature

“…Note that the experiments described here were done using only DAFP-1 and trehalose in water, whereas hemolymph is a very complex system. These results suggest that trehalose also functions as a physiological antifreeze activity enhancer, working in cooperation with certain other solutes in the winter hemolymph to depress the freezing and supercooling points to sufficiently lower temperatures for D. canadensis wintering (39,40).…”

Surface stiffening and enhanced photoluminescence of ion implanted cellulose – polyvinyl alcohol – silica composite

“…The control of ice nucleation is essential to engineer the porous morphology of the scaffolds. The antifreezing substances such as anti freezing proteins and salts like zirconium acetates are the important class of materials which controls the ice nucleation by the exposure of hydrophobic residues on ice nuclei (Duman, 2015;Mizrahy, Dolev, Guy, & Braslavsky, 2013). The pore structure is mainly controlled by the ice nucleation, which is influenced by various parameters such as solution viscosity, concentration of the solute, growth velocity of ice crystals and pH.…”

Interaction of ice binding proteins with ice, water and ions

“…13,25 At first sight, it seems as if fishes are well protected from freezing in sea water of À1. 9 C, while insects remain at risk in their natural habitats.…”

“…Insect AFPs from freezetolerant species exhibit much lower TH values than their counterparts from freeze-avoiding species. 25 A combination of low daylight exposure and low temperature triggers the production of AFPs in cold-adapted overwintering plants with typical TH values of 0.1-0.5 C. 31,35 Plant IBPs are also very effective inhibitors of ice recrystallization [ Fig. 1(e)].…”