Puff N, Cagna A, Aguié-Béghin V, Douillard R
Équipe de Biochimie des Macromolécules Végétales, INRA, Centre de Recherche Agronomique, 2 Esplanade Roland Garros, Reims Cedex 2, 51686, France
J Colloid Interface Sci. 1998 Dec 15;208(2):405-414. doi: 10.1006/jcis.1998.5846.
The adsorption of beta-casein at the air-solution interface has been monitored in equilibrium conditions by neutron reflectivity. It was observed that for a bulk concentration of 100 mg/L, the amount of protein adsorbed per unit surface increases from 2.8 to 4.4 mg/m2 when the ethanol concentration in the bulk changes from 0 to 20% (v/v). Surface pressure measurements on aqueous solutions indicate that the surface pressure is higher when both protein and alcohol are added than when a single substance is in the solution. The addition of protein has an effect when the alcohol concentration is less than 20%. These results are consistent with the occurrence at the interface of a protein network leaving a surface fraction available for ethanol. A thermodynamic model has been developed using scaling law arguments to model the surface pressure and dilational modulus measurements. It introduces an exponent which is characteristic of the solvent "quality" and of the structure of the interfacial layer. The results are interpreted as showing that ethanol modifies the solvent properties, the interactions between the protein and the solvent, and the structure of the adsorption layer. The main transition seems to occurr at 6% ethanol. Copyright 1998 Academic Press.
通过中子反射率在平衡条件下监测了β-酪蛋白在气-液界面的吸附情况。观察到，对于100 mg/L的本体浓度，当本体中的乙醇浓度从0%（v/v）变为20%（v/v）时，单位表面吸附的蛋白量从2.8 mg/m²增加到4.4 mg/m²。对水溶液进行的表面压力测量表明，同时添加蛋白质和乙醇时的表面压力高于溶液中仅含有单一物质时的表面压力。当乙醇浓度小于20%时，添加蛋白质会产生影响。这些结果与在界面处形成蛋白质网络从而为乙醇留出表面部分的情况一致。利用标度律论证开发了一个热力学模型，以对表面压力和扩张模量测量进行建模。该模型引入了一个指数，该指数是溶剂“质量”和界面层结构的特征。结果表明，乙醇改变了溶剂性质、蛋白质与溶剂之间的相互作用以及吸附层的结构。主要转变似乎发生在乙醇浓度为6%时。版权所有1998年，学术出版社。
