Polysaccharide charge density regulating protein adsorption to air/water interfaces by protein/polysaccharide complex formation
Polysaccharide charge density regulating protein adsorption to air/water interfaces by protein/polysaccharide complex formation
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DOI：
10.1021/jp075441k
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发表时间：
2007-11-15
影响因子：
3.3
通讯作者：
de Jongh, Harmen H. J.
中科院分区：
文献类型：
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作者：
Ganzevles, Renate A.;Kosters, Hans;de Jongh, Harmen H. J.
由于蛋白质/多糖复合物的形成是由静电相互作用主导的，多糖电荷密度预计将在复合物的吸附行为中起主要作用。在这项研究中，支链淀粉（一种不带电荷的多糖）羧化到四个不同的电荷密度（羧化亚基的分数：0.1，0.26，0.51，和0.56）被用来研究电荷密度的影响上的混合蛋白质/多糖吸附层的性质在空气/水界面。与所有的普鲁兰样品，可溶性复合物与β-乳球蛋白可以形成在低离子强度，pH 4.5。结果表明，与纯β-乳球蛋白相比，普鲁兰多糖的电荷密度越高，表面压力随时间的增加被延迟得越多。延迟甚至更明显的发展的伸缩模量。较低的结晶模量可以通过多糖防止由于静电排斥而在空气/水界面处形成致密蛋白质层的能力来解释。多糖防止“层致密性”的这种能力随着复合物的净负电荷而增加。如果电荷密度足够（>= 0.26），多糖可以增强吸附层内复合物之间的凝聚力。多糖的电荷密度被证明是一个占主导地位的调节剂的吸附动力学以及由此产生的表面流变学行为的混合层形成。这些研究结果对复杂蛋白质多糖体系的应用具有重要价值。
Because the formation of protein/polysaccharide complexes is dominated by electrostatic interaction, polysaccharide charge density is expected to play a major role in the adsorption behavior of the complexes. In this study, pullulan (a non-charged polysaccharide) carboxylated to four different charge densities (fraction of carboxylated subunits: 0.1, 0.26, 0.51, and 0.56) was used to investigate the effect of charge density on the properties of mixed protein/polysaccharide adsorbed layers at air/water interfaces. With all pullulan samples, soluble complexes with beta-lactoglobulin could be formed at low ionic strength, pH 4.5. It was shown that the higher was the pullulan charge density, the more the increase of surface pressure in time was retarded as compared to that for pure beta-lactoglobulin. The retardation was even more pronounced for the development of the dilatational modulus. The lower dilatational modulus can be explained by the ability of the polysaccharides to prevent the formation of a compact protein layer at the air/water interface due to electrostatic repulsion. This ability of the polysaccharides to prevent "layer compactness" increases with the net negative charge of the complexes. If charge density is sufficient (>= 0.26), polysaccharides may enhance the cohesion between complexes within the adsorbed layer. The charge density of polysaccharides is shown to be a dominant regulator of both the adsorption kinetics as well as the resulting surface theological behavior of the mixed layers formed. These findings have significant value for the application of complex protein polysaccharide systems.