A Theoratical Study For Thermal Hysteresis Of Afpi Used Statistical Thermodynamics

Antifreeze proteins(AFPs)is a class of proteins found in organisms that live in cold environment.There are various structures of AFPs.AFPs can adsorb to the surface of ice crystal in aqueous solution,and inhibit growth and recrystallization of ice crystal.AFPs can reduce freezing temperature with non-colligative effect,and have no impact on the melting temperature of ice crystal.The difference between the reduced freezing temperature and the melting temperature is the thermal hysteresis(TH).Thermal hysteresis is used as a measure of the specific activity of these AFPs.Based on statistical thermodynamic theory and Gibbs-Thomson effect for growth of ice crystal in AFP solution,the thermal hysteresis activity of three kinds of AFPI molecules(AFP9,HPLC-6,AAAA2 k E)have been studied?According statistical thermodynamic theory,the probability distribution of number of AFPI molecules that adsorbed on surface of ice crystals is analyzed at different concentration.The statistical average of the number of APFI molecules adsorbed to the surface of ice crystals is calculated.The relationship between number of adsorbed APFI molecules and concentration of AFPI solution is obtained.Based on the statistical distribution of the number of APFI molecules adsorbed to the surface of ice crystal,the statistical average of neighboring distances of AFPI molecules is obtained.By using the Gibbs-Thomson effect for growth of ice crystals in AFP solution and the statistical thermodynamic analysis results of the average of neighboring distance of AFPI molecules,thermal hysteresis activities of AFPI molecules are calculated at different concentrations.The theoretical study results are fit with experiment results.The results obtained in this work are valuable for understanding the mechanism of thermal hysteresis activity of AFPs.