Hansen T N, Carpenter J F
Cryolife, Incorporated, Marietta, Georgia 30067.
Biophys J. 1993 Jun;64(6):1843-50. doi: 10.1016/S0006-3495(93)81555-8.
Differential scanning calorimetry and cryomicroscopy were used to investigate the effects of type I antifreeze protein (AFP) from winter flounder on 58% solutions of hydroxyethyl starch. The glass, devitrification, and melt transitions noted during rewarming were unaffected by 100 micrograms/ml AFP. Isothermal annealing experiments were undertaken to detect the effects of AFP-induced inhibition of ice crystal growth using calorimetry. A premelt endothermic peak was detected during warming after the annealing procedure. Increasing the duration or the temperature of the annealing for the temperature range from -28 and -18 degrees C resulted in a gradual increase in the enthalpy of the premelt endotherm. This transition was unaffected by 100 micrograms/ml AFP. Annealing between -18 and -10 degrees C resulted in a gradual decrease in the premelt peak enthalpy. This process was inhibited by 100 micrograms/ml AFP. Cryomicroscopic examination of the samples revealed that AFP inhibited ice recrystallization during isothermal annealing at -10 degrees C. Annealing at lower temperatures resulted in minimal ice recrystallization and no visible effect of AFP. Thus, the 100 micrograms/ml AFP to have a detectable influence on thermal events in the calorimeter, conditions must be used that result in significant ice growth without AFP and visible inhibition of this process by AFP.
采用差示扫描量热法和低温显微镜法研究了来自冬鲽的I型抗冻蛋白（AFP）对羟乙基淀粉58%溶液的影响。复温过程中观察到的玻璃化转变、反玻璃化转变和熔融转变不受100微克/毫升AFP的影响。进行等温退火实验以利用量热法检测AFP诱导的冰晶生长抑制作用。退火程序后的升温过程中检测到一个预熔融吸热峰。在-28至-18摄氏度的温度范围内增加退火持续时间或温度会导致预熔融吸热峰的焓逐渐增加。这种转变不受100微克/毫升AFP的影响。在-18至-10摄氏度之间退火会导致预熔融峰焓逐渐降低。此过程受到100微克/毫升AFP的抑制。对样品进行的低温显微镜检查表明，AFP在-10摄氏度等温退火期间抑制了冰的再结晶。在较低温度下退火导致冰的再结晶极少，且AFP无明显作用。因此，要使100微克/毫升AFP对量热计中的热事件产生可检测的影响，必须使用在无AFP时会导致显著冰生长且AFP能明显抑制此过程的条件。
