Svendsen Ida E, Lindh Liselott, Arnebrant Thomas
Biomedical Laboratory Science, Faculty of Health and Society, Malmö University, SE-205 06 Malmö, Sweden.
Colloids Surf B Biointerfaces. 2006 Dec 1;53(2):157-66. doi: 10.1016/j.colsurfb.2006.08.016. Epub 2006 Aug 30.
Adsorption of the cationic salivary proteins lactoferrin, lactoperoxidase, lysozyme and histatin 5 to pure (hydrophilic) and methylated (hydrophobized) silica surfaces was investigated by in situ ellipsometry. Effects of concentration (</=10 microgml(-1), for lysozyme </=200 microgml(-1)) and dependence of surface wettability, as well as adsorption kinetics and elutability of adsorbed films by buffer and sodium dodecyl sulphate (SDS) solutions were investigated. Results showed that the amounts adsorbed decreased in the order lactoferrin>/=lactoperoxidase>lysozyme>/=histatin 5. On hydrophilic silica, the adsorption was most likely driven by electrostatic interactions, which resulted in adsorbed amounts of lactoferrin that indicated the formation of a monolayer with both side-on and end-on adsorbed molecules. For lactoperoxidase the adsorbed amounts were somewhat higher than an end-on monolayer, lysozyme adsorption showed amounts corresponding to a side-on monolayer, and histatin 5 displayed adsorbed amounts in the range of a side-on monolayer. On hydrophobized substrata, the adsorption was also mediated by hydrophobic interactions, which resulted in lower adsorbed amounts of lactoferrin and lactoperoxidase; closer to side-on monolayer coverage. For both lysozyme and histatin 5 the adsorbed amounts were the same as on the hydrophilic silica. The investigated proteins exhibited fast adsorption kinetics, and the initial kinetics indicated mass transport controlled behaviour at low concentrations on both types of substrates. Buffer rinsing and SDS elution indicated that the proteins in general were more tightly bound to the hydrophobized surface compared to hydrophilic silica. Overall, the surface activity of the investigated proteins implicates their importance in the salivary film formation.
通过原位椭圆偏振技术研究了阳离子唾液蛋白乳铁蛋白、乳过氧化物酶、溶菌酶和组蛋白5在纯（亲水性）和甲基化（疏水性）二氧化硅表面的吸附情况。研究了浓度（溶菌酶≤200μg/ml，其他≤10μg/ml）、表面润湿性的影响，以及吸附动力学和缓冲液及十二烷基硫酸钠（SDS）溶液对吸附膜的洗脱能力。结果表明，吸附量按乳铁蛋白≥乳过氧化物酶＞溶菌酶≥组蛋白5的顺序降低。在亲水性二氧化硅上，吸附最有可能由静电相互作用驱动，这导致乳铁蛋白的吸附量表明形成了一个由侧立吸附和端立吸附分子组成的单层。对于乳过氧化物酶，吸附量略高于端立单层，溶菌酶吸附量对应于侧立单层，组蛋白5的吸附量在侧立单层范围内。在疏水化基质上，吸附也由疏水相互作用介导，这导致乳铁蛋白和乳过氧化物酶的吸附量较低；更接近侧立单层覆盖。对于溶菌酶和组蛋白5，吸附量与亲水性二氧化硅上相同。所研究的蛋白质表现出快速的吸附动力学，初始动力学表明在两种类型的底物上低浓度时受传质控制。缓冲液冲洗和SDS洗脱表明，与亲水性二氧化硅相比，蛋白质通常与疏水化表面结合更紧密。总体而言，所研究蛋白质的表面活性表明它们在唾液膜形成中具有重要作用。
