Sarkar D, Chattoraj D K
Department of Food Technology & Biochemical Engineering, Jadavpur University, Calcutta.
Indian J Biochem Biophys. 1996 Feb;33(1):39-47.
The kinetics of adsorption of soluble denatured protein, gelatin has been studied at the alumina-water interface as a function of protein concentration, pH, temperature and ionic strength. The rate of adsorption of gelatin has been compared with rate of adsorption of BSA denatured by 8 M urea or 0.05 M SDS. The initial stage for the adsorption process is diffusion-controlled and the surface diffusion coefficients evaluated from equations of Ward and Tordai and by Bull for globular and denatured proteins are found to be widely different from each other. The kinetic data for gelatin fit into a first order rate equation with two rate constants, k1a and k2a. Using Arrhenius equation, the activation energies delta E1* and delta E2* have been evaluated from the values of k1a and k2a respectively. The corresponding changes in values of enthalpy of activation (delta H*), entropy of activation (delta S*) and free energy of activation (delta G*) have been evaluated using Eyring's equation for absolute reaction rate. It has been found that for both gelatin and denatured BSA, in the first kinetic step delta H1* > T delta S1* and for the second step T delta S2* > delta H2.
在氧化铝 - 水界面研究了可溶性变性蛋白明胶的吸附动力学，考察了其作为蛋白浓度、pH值、温度和离子强度的函数关系。将明胶的吸附速率与经8 M尿素或0.05 M SDS变性的牛血清白蛋白（BSA）的吸附速率进行了比较。吸附过程的初始阶段受扩散控制，通过沃德（Ward）和托尔代（Tordai）方程以及布尔（Bull）方程计算得到的球状蛋白和变性蛋白的表面扩散系数差异很大。明胶的动力学数据符合具有两个速率常数k1a和k2a的一级速率方程。利用阿伦尼乌斯方程，分别从k1a和k2a的值计算出活化能ΔE1和ΔE2。使用艾林（Eyring）的绝对反应速率方程计算了活化焓（ΔH*）、活化熵（ΔS*）和活化自由能（ΔG*）的相应变化。结果发现，对于明胶和变性BSA，在第一个动力学步骤中ΔH1* > TΔS1*，在第二个步骤中TΔS2* > ΔH2。
