Thermal hysteresis (TH), a difference between the melting and freezing points of a solution that is indicative of the presence of large-molecular-mass antifreezes (e.g., antifreeze proteins), has been described in animals, plants, bacteria, and fungi. Although all previously described TH-producing biomolecules are proteins, most thermal hysteresis factors (THFs) have not yet been structurally c...

Microgravity experiments for ice crystal growth were conducted twice in the Japan Experiment Module “Kibo” of the International Space Station. Experimental cartridges newly developed for each experiment were transported to the space station and installed in the SCOF facility. All of the experiments were possibly could be performed by using a tele-control system on the ground. Crystal patterns d...

Antifreeze proteins are found in a wide range of overwintering plants where they inhibit the growth and recrystallization of ice that forms in intercellular spaces. Unlike antifreeze proteins found in fish and insects, plant antifreeze proteins have multiple, hydrophilic ice-binding domains. Surprisingly, antifreeze proteins from plants are homologous to pathogenesis-related proteins and also p...

Class I chitinases hydrolyse the β-1,4-linkage of chitin and also acquire antifreeze activity in some of the overwintering plants during cold stress. Two chitinases, HrCHT1a of 31 kDa and HrCHT1b of 34 kDa, were purified from cold acclimated and non-acclimated seabuckthorn seedlings using chitin affinity chromatography. 2-D gels of HrCHT1a and HrCHT1b showed single spots with pIs 7.0 and 4.6 re...

The solution structure of a synthetic mutant type I antifreeze protein (AFP I) was determined in aqueous solution at pH 7.0 using nuclear magnetic resonance (NMR) spectroscopy. The mutations comprised the replacement of the four Thr residues by Val and the introduction of two additional Lys-Glu salt bridges. The antifreeze activity of this mutant peptide, VVVV2KE, has been previously shown to b...

Antifreeze proteins (AFPs) adsorb to the surface of embryonic ice crystals prevent their growth. The protein-ice adsorption lowers freezing point solution. Then, a thermal hysteresis can be defined as difference between melting and temperatures. This quantity is measure antifreeze protein activity. In this sense, there exists evidence that activity enhances with increasing area/length ice-bindi...

Injury inflicted by frost and freezing is found in all plants exposed to such damaging temperatures. Antifreeze proteins protect against these injurious temperatures by providing freeze resistance to organisms in which they occur. The expression of antifreeze proteins in a plant is a possible means of increasing the frost resistance and freeze tolerance of plants. Freeze tolerance curves of non...

An Arg-containing antifreeze glycoprotein from the polar fish Eleginus gracilis was isolated, and the major components were purified to homogeneity. The general protocol for purification was chromatography of serum on DEAE-cellulose, followed by chromatography on a cation exchanger. DEAE-cellulose chromatography resulted in two fractions, A and B. Fraction A contained most of the antifreeze gly...

The serum of winter flounder contains a group of antifreeze peptides which lower the freezing point of their body fluid in the winter. These antifreeze peptides disappear from their serum in the summer when the water temperature rises. Messenger RNA isolated from the liver of flounder collected in January directs the synthesis of predominantly one protein in an in vitro protein synthesis system...

It has been suggested that above a critical protein concentration, fish Type III antifreeze protein (AFP III) self-assembles to form micelle-like structures that may play a key role in antifreeze activity. To understand the complex activity of AFP III, a comprehensive description of its association state and structural organization in solution is necessary. We used analytical ultracentrifugatio...