Hajra S, Chattoraj D K
Department of Food Technology & Biochemical Engineering, Jadavpur University, Calcutta.
Indian J Biochem Biophys. 1991 Apr;28(2):124-32.
Extent of adsorption of proteins at alumina-water interface from solutions containing binary mixture of beta-lactoglobulin and bovine serum albumin (BSA), beta-lactoglobulin and gelatin, and gelatin and bovine serum albumin has been estimated as functions of protein concentrations at varying pH, ionic strength, temperature and weight fraction ratios of protein mixture. The extent of adsorption (gamma lacw) of lactoglobulin in the presence of BSA increases with increase of protein concentration (Clac) until it reaches a maximum but a fixed value gamma lacw(m). Extent of adsorption gamma serw also initially increases with increase of protein concentrations until it reaches maximum value gamma serw(m). Beyond these protein concentrations, adsorbed BSA is gradually desorbed due to the preferential adsorption of lactoglobulin from the protein mixture. In many systems, gamma serw at high protein concentrations even becomes negative due to the strong competition of BSA and water for binding to the surface sites in the presence of lactoglobulin. For lactoglobulin-gelatin mixtures, adsorption of both proteins is enhanced as protein concentration is increased until limiting values for adsorption are reached. Beyond the limiting value, lactoglobulin is further accumulated at the interface without limit when protein concentration is high. For gelatin-albumin mixtures, extent of gelatin adsorption increases with increase in the adsorption of BSA. The limit for saturation of adsorption for gelatin is not reached for many systems. At acid pH, adsorbed BSA appears to be desorbed from the surface in the presence of gelatin. From the results thus obtained the role of electrostatic and hydrophobic effects in controlling the adsorption process has been analysed.
已估算了在不同pH值、离子强度、温度以及蛋白质混合物重量分数比条件下，β-乳球蛋白与牛血清白蛋白（BSA）、β-乳球蛋白与明胶、明胶与牛血清白蛋白的二元混合溶液中蛋白质在氧化铝-水界面的吸附程度与蛋白质浓度的函数关系。在BSA存在的情况下，乳球蛋白的吸附程度（γlacw）随着蛋白质浓度（Clac）的增加而增加，直至达到最大值γlacw(m)，但该值是固定的。血清白蛋白的吸附程度γserw最初也随着蛋白质浓度的增加而增加，直至达到最大值γserw(m)。超过这些蛋白质浓度后，由于蛋白质混合物中乳球蛋白的优先吸附，吸附的BSA会逐渐解吸。在许多体系中，由于在乳球蛋白存在时BSA与水对表面位点结合的强烈竞争，高蛋白浓度下的γserw甚至会变为负值。对于乳球蛋白-明胶混合物，随着蛋白质浓度的增加，两种蛋白质的吸附均增强，直至达到吸附极限值。超过极限值后，当蛋白质浓度较高时，乳球蛋白会在界面处无限制地进一步积累。对于明胶-白蛋白混合物，明胶的吸附程度随着BSA吸附量的增加而增加。许多体系未达到明胶吸附饱和的极限。在酸性pH值下，在明胶存在时，吸附的BSA似乎会从表面解吸。根据所得结果，分析了静电和疏水作用在控制吸附过程中的作用。
