Polysaccharide Charge Density Regulating Protein Adsorption to Air/Water Interfaces by Protein/Polysaccharide Complex Formation

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• 作者：Renate A. Ganzevles ; Hans Kosters ; Ton van Vliet ; Martien A. Cohen Stuart ; Harmen H. J. de Jongh
• 刊名：Journal of Physical Chemistry B
• 出版年：2007
• 出版时间：November 15, 2007
• 年：2007
• 卷：111
• 期：45
• 页码：12969 - 12976
• 全文大小：151K
• 年卷期：v.111,no.45(November 15, 2007)
• ISSN：1520-5207

文摘

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 (fractionof carboxylated subunits: 0.1, 0.26, 0.51, and 0.56) was used to investigate the effect of charge density onthe properties of mixed protein/polysaccharide adsorbed layers at air/water interfaces. With all pullulan samples,soluble complexes with -lactoglobulin could be formed at low ionic strength, pH 4.5. It was shown that thehigher was the pullulan charge density, the more the increase of surface pressure in time was retarded ascompared to that for pure -lactoglobulin. The retardation was even more pronounced for the developmentof the dilatational modulus. The lower dilatational modulus can be explained by the ability of thepolysaccharides to prevent the formation of a compact protein layer at the air/water interface due to electrostaticrepulsion. This ability of the polysaccharides to prevent "layer compactness" increases with the net negativecharge of the complexes. If charge density is sufficient (0.26), polysaccharides may enhance the cohesionbetween complexes within the adsorbed layer. The charge density of polysaccharides is shown to be a dominantregulator of both the adsorption kinetics as well as the resulting surface rheological behavior of the mixedlayers formed. These findings have significant value for the application of complex protein-polysaccharidesystems.