Max-Planck-Institut für Kolloid- und Grenzflächenforschung, 14424 Potsdam, Germany.
Langmuir. 2011 Feb 1;27(3):965-71. doi: 10.1021/la1040757. Epub 2010 Dec 28.
Interfacial tension measurements have been performed at the water/hexane interface on mixtures of the bovine milk protein β-lactoglobulin and positively charged cationic surfactants (alkytrimethylammonium bromides). The addition of surfactants with different chain lengths leads to the formation of protein-surfactant complexes with different adsorption properties as compared to those of the single protein. In this study, the formation of complexes has been observed clearly for protein-long chain surfactant (TTAB and CTAB) mixtures, which has shown in addition to specific electrostatic interactions the relevance of hydrophobic interactions between surfactant molecules and the protein. The modeling of interfacial tension data by using a mixed adsorption model provides a quantitative understanding of the mixture behavior. Indeed, the value of the adsorption constant of the protein obtained in the presence of surfactants has strongly varied as compared to the single protein. Actually, this parameter which represents the affinity of the molecule for the interface is representative of the hydrophobic character of the compound and so of its surface activity. Even if a more hydrophobic and more surface active protein-surfactant complex has been formed, the replacement of this complex from the interface by surfactants close to their cmc was observed.
已经在水/己烷界面上对牛乳蛋白β-乳球蛋白和带正电荷的阳离子表面活性剂（烷基三甲基溴化铵）的混合物进行了界面张力测量。与单一蛋白质相比，添加具有不同链长的表面活性剂会导致形成具有不同吸附特性的蛋白质-表面活性剂复合物。在这项研究中，对于蛋白质-长链表面活性剂（TTAB 和 CTAB）混合物，清楚地观察到了复合物的形成，这表明除了特定的静电相互作用之外，表面活性剂分子与蛋白质之间的疏水相互作用也很重要。通过使用混合吸附模型对界面张力数据进行建模，可以定量理解混合物的行为。实际上，与单一蛋白质相比，在存在表面活性剂的情况下获得的蛋白质吸附常数的值发生了很大变化。实际上，该参数代表分子与界面的亲和力，是化合物疏水性的代表，也是其表面活性的代表。即使形成了更疏水和更具表面活性的蛋白质-表面活性剂复合物，也观察到了由接近 cmc 的表面活性剂取代该复合物从界面上的情况。
