Department of Physics , Kindai University , 3-4-1 Kowakae , Higashiosaka City , Osaka 577-8502 , Japan.
Department of Physics , Tokyo Gakugei University , 4-1-1 Nukuikita-machi , Koganei , Tokyo 184-8501 , Japan.
J Phys Chem B. 2018 May 3;122(17):4662-4666. doi: 10.1021/acs.jpcb.8b01039. Epub 2018 Apr 20.
We present the results of time-resolved X-ray reflectivity measurements carried out to investigate the early stage of protein adsorption and deformation at an air-water interface. Three globular proteins [lysozyme, myoglobin, and bovine serum albumin (BSA)] were studied, and we observed that the proteins adsorbed at the air-water interface initially possessed a thinner conformation than their native structures. The degree of deformation increased in the order myoglobin < lysozyme < BSA, which was inconsistent with the order of molecular flexibility. The initial rate of protein adsorption increased in the order lysozyme < BSA < myoglobin as determined by the dynamic surface tension. More flexible proteins generally adsorb at the interface more rapidly; however, proteins with hydrophobic patches on the protein surface, such as myoglobin, adsorb at the interface with little deformation. These results provide evidence that protein unfolding during adsorption only takes place if the kinetics of adsorption are similar to or slower than the kinetics of unfolding.
我们呈现了进行时间分辨 X 射线反射率测量的结果，以研究蛋白质在气液界面上的吸附和变形的早期阶段。研究了三种球状蛋白质[溶菌酶、肌红蛋白和牛血清白蛋白（BSA）]，我们观察到，在气液界面上吸附的蛋白质最初具有比其天然结构更薄的构象。变形程度按肌红蛋白<溶菌酶<BSA 的顺序增加，这与分子柔韧性的顺序不一致。通过动态表面张力测定，蛋白质吸附的初始速率按溶菌酶<BSA<肌红蛋白的顺序增加。通常，更灵活的蛋白质在界面上的吸附速度更快；然而，在蛋白质表面上具有疏水性斑点的蛋白质，如肌红蛋白，在界面上的吸附变形很小。这些结果表明，只有在吸附动力学与展开动力学相似或更慢的情况下，蛋白质在吸附过程中才会展开。
