In contrast, strategy used by cold loving organism to survive freezing temperature is the production of anti-nucleating proteins or antifreeze proteins (AFPs). These are structurally diverse group of proteins that have the ability to modify ice crystal structure. Unlike the widely used automotive antifreeze, ethylene glycol, AFPs do not lower freezing point in proportion to concentration. Rather, they work in a non-colligative manner. This allows them to act as antifreeze at concentrations 300-500 times lowers than other dissolved solutes. This minimizes their effect on osmotic pressure. The unusual capabilities of AFPs are attributed to their binding ability at specific ice crystal surfaces. AFPs create a difference between the melting point and freezing point known as thermal hysteresis (TH) is a measure of the antifreeze activity. The addition of AFPs at the interface between solid ice and liquid water inhibits the thermodynamically favored growth of the ice crystal. Ice growth is kinetically inhibited by the AFPs covering the water-accessible surfaces of ice. This mechanism is also known as freeze avoidance. Besides causing TH, the AFPs act by another mechanism called freeze tolerance. In most of the freezing conditions, formation of ice takes place as a multicrystalline mass. Growth of large ice crystals occurs at the expense of smaller crystals, a phenomenon termed ice recrystallization. AFPs limit the growth of ice crystals at sub-zero temperatures by being adsorbed on the ice surface. This mechanism is known as recrystallization inhibition (RI).
Antarticine-NF3 is a glycoprotein with antifreeze properties produced by the bacterium Pseudoalteromonas Antarctica that has been patented by Spanish researchers. It was found that Antarticine is effective for scar treatments and re-epithelialization of wounds. This glycoprotein is now included in some cosmetic regeneration creams (sometimes under the name Antarctilyne). It is also proposed in association with edelweiss extract: this is of course reminiscent of the peculiar resistance to harsh conditions of both the Antarctic bacterium and the Alp flower. The extracts of the Antarctic algae Durvillea Antarctica are included in cosmetics creams to improve skin vitality such as in the Extra Firming Day Cream, a top seller of Clarins (France). The successful business endeavor has been the introduction of AFPs into ice cream and yogurt products. AFPs allow the production of very creamy, dense, reduced fat ice cream with fewer additives. They control ice crystal growth brought on by thawing on the loading dock or kitchen table which drastically reduces texture quality).
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