antifreeze molecule

A Dictionary of Biology

antifreeze molecule Any substance produced by an organism in order to prevent freezing of its tissues or body fluids when subject to subzero environmental temperatures. Many animals living in cold climates adopt a strategy of preventing ice formation in their tissues when subject to freezing conditions. One way of achieving this is to accumulate solutes in their blood, thereby raising the osmotic concentration and so depressing the supercooling point. Salts and sugars contribute to this, but organisms also produce relatively inert molecules, notably glycerol and other polyhydric alcohols (polyols), such as sorbitol and ribitol, specifically for this purpose. For example, high concentrations of glycerol can enable the survival of certain cold-hardy invertebrates at temperatures as low as –60°C. Some families of teleost fish inhabiting polar regions manufacture antifreeze peptides or antifreeze glycopeptides, which are effective antifreeze agents at relatively low concentrations. They bind to the edges of ice crystal lattices and prevent the addition of further water molecules, causing a phenomenon termed ‘thermal hysteresis’, in which the freezing point is depressed well below the melting point – hence these peptides are also called thermal hysteresis proteins. Similar peptides occur in certain insects, spiders, and mites. See also cryoprotectant.

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© A Dictionary of Biology 2004, originally published by Oxford University Press 2004.

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	Activity of a Two-Domain Antifreeze Protein Is Not Dependent on Linker Sequence ; ...of each other. Nevertheless, the thermal hysteresis activity of the modified protein...melting temperatures is termed the thermal hysteresis and is the most common measure of...repeats has been observed to have thermal hysteresis activity (8,9). Houston et al. did... Read more
	Structure of type I antifreeze protein and mutants in supercooled water ; ...AFPs) in the serum, also known as thermal hysteresis proteins, which prevent the formation...the melting point and is known as thermal hysteresis. To measure the amount of thermal hysteresis of a particular AFP, the temperature... Read more
	A theoretical model of a plant antifreeze protein from Lolium perenne ; ...inhibition activity but relatively low thermal hysteresis activity. We present here a theoretical...explanation for the protein's inferior thermal hysteresis but superior ice recrystallization...the range of which is known as the thermal hysteresis (TH)), ice expansion along these... Read more
	Structural Modeling of Snow Flea Antifreeze Protein ; ...the melting point of its solution (thermal hysteresis). BLAST searches did not detect any...organism's death. AFPs, also known as thermal hysteresis proteins (2), bind to a growing ice...Both of these proteins had potent thermal hysteresis activities of >2 C at micromolar... Read more
	The dynamics, structure, and conformational free energy of proline-containing antifreeze glycoprotein ; ...noncolligative manner, to exhibit thermal hysteresis, which lowers the freezing temperature...melting temperature. Furthermore, the thermal hysteresis is additive to the colligative effect...ice may not be responsible for the thermal hysteresis. Thus, the exact molecular mechanism... Read more
	The MEMS generation takes its place beside quartz.(SPECIAL FEATURE) ; ...long-term frequency stability and thermal hysteresis, have convinced some design engineers...their superior temperature stability, thermal hysteresis, and long-term stability. But quartz...exhibit good temperature stability, thermal hysteresis, and long-term stability. Now that... Read more
	MEMS GENERATION TAKES ITS PLACE BESIDE QUARTZ. ; ...long-term frequency stability and thermal hysteresis, have convinced some design engineers...their superior temperature stability, thermal hysteresis, and long term stability. But quartz...exhibit good temperature stability, thermal hysteresis, and long-term stability. Now that... Read more
	Fluorescence Microscopy Evidence for Quasi-Permanent Attachment of Antifreeze Proteins to Ice Surfaces ; ...usually characterized by measuring its thermal hysteresis, i.e., the extent to which the nonequilibrium...reduced below the melting point. The thermal hysteresis of AFPs varies as a function of concentration...the melting point, and within this thermal hysteresis gap, the ice ... Read more
	MEMS oscillators earn their stripes: for more than 50 years, quartz oscillators dominated the marketplace. Now it's silicon's turn.(MATERIALS SCIENCE/NANOTECHNOLOGY) ; ...however, such as improved long-term frequency stability and thermal hysteresis, have convincingly made the case for MEMS. R&D Magazine...match quartz resonators. Superior temperature stability, thermal hysteresis, and long-term stability all conspired to guarantee its... Read more
	Strain gage behavior on sandwich glasses ; ...conducted to measure strain gage thermal hysteresis and thermal drift. When examining thermal hysteresis, the plates and samples were first...stops were made at + 500degC. The thermal hysteresis was calculated by comparing the... Read more

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	thermal hysteresis protein thermal hysteresis protein See antifreeze molecule . Read more
	polyol ...to the sugar alcohols, which include such biologically important molecules as myo - inositol glycerol , sorbitol (common in the fruits of many...Certain polyols act as osmolytes in the kidney cells or function as antifreeze molecules . Read more
	glycerol ...liquid, miscible with water but insoluble in ether. It is widely distributed in all living organisms as a constituent of the glycerides , which yield glycerol when hydrolysed. Glycerol itself is used as an antifreeze molecule by certain organisms. Read more
	cryoprotectant ...turtles. One group of these substances consists of antifreeze molecules , notably glycerol and related polyhydric alcohols...membranes within cells and prevent the binding of water molecules, so preserving the integrity of cell structures... Read more
	supercooling ...crystals. Hence, animals preparing for winter frequently void their gut contents. Second, the animal manufactures antifreeze molecules , such as glycerol, which depress the freezing point. These measures can be extremely effective in achieving supercooling... Read more

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