Funakoshi Kunio, Inada Takaaki, Kawabata Hiroshi, Tomita Takashi
National Institute of Advanced Industrial Science and Technology, 1-2-1 Namiki, Tsukuba, Ibaraki 305-8564, Japan.
Biomacromolecules. 2008 Nov;9(11):3150-6. doi: 10.1021/bm800739s. Epub 2008 Oct 11.
Activity of antifreeze proteins (AFPs) and antifreeze glycoproteins (AFGPs) is often determined by thermal hysteresis, which is the difference between the melting temperature and the nonequilibrium freezing temperature of ice in AF(G)P solutions. In this study, we confirmed that thermal hysteresis of AFP type I is significantly enhanced by a cooperative function of ammonium polyacrylate (NH4PA). Thermal hysteresis of mixtures of AFP type I and NH4PA was much larger than the sum of each thermal hysteresis of AFP type I and NH4PA alone. In mixed solutions of AFP type I and NH4PA in the thermal hysteresis region, hexagonal pyramidal-shaped pits densely formed on ice surfaces close to the basal planes. The experimental results suggest that the cooperative function of NH4PA with AFP type I was caused either by the increase in adsorption sites of AFP type I on ice or by the adsorption of AFP type I aggregates on ice.
抗冻蛋白（AFPs）和抗冻糖蛋白（AFGPs）的活性通常由热滞来确定，热滞是指AF（G）P溶液中冰的熔点温度与非平衡冻结温度之间的差值。在本研究中，我们证实了聚丙烯酸铵（NH4PA）的协同作用显著增强了I型抗冻蛋白的热滞。I型抗冻蛋白与NH4PA混合物的热滞远大于I型抗冻蛋白和NH4PA各自热滞的总和。在热滞区域的I型抗冻蛋白和NH4PA混合溶液中，靠近基面的冰表面密集形成六角锥形凹坑。实验结果表明，NH4PA与I型抗冻蛋白的协同作用是由I型抗冻蛋白在冰上吸附位点的增加或I型抗冻蛋白聚集体在冰上的吸附引起的。
