Haggerty L, Lenhoff A M
Department of Chemical Engineering, University of Delaware, Newark 19716.
Biophys J. 1993 Mar;64(3):886-95. doi: 10.1016/S0006-3495(93)81448-6.
Scanning tunneling microscopy (STM) has been used to observe lysozyme at a graphite surface directly in order to gain mechanistic information about the molecular events involved in protein adsorption. The experiments were performed using an insulated tip in an aqueous protein solution, allowing the time course of the adsorption process to be followed, including the evolution of ordered arrays. Ordered arrays of protein molecules were observed, with lattice spacings that varied with bulk protein concentration and salt strength. Fourier analysis was used to determine the average cell dimensions of an array. From the observed lattice spacings, it was possible to estimate the surface coverage of the protein, and thus, by varying the conditions, adsorption isotherms could be obtained. These isotherms compare well with adsorption isotherms measured using total internal reflectance fluorescence (TIRF) spectroscopy on a hydrophobic surface. Since the protein is charged and the electrolyte has an effect on the isotherms, electrostatics are a likely controlling factor. Molecular electrostatics computations were thus used to investigate the possible origins of the lattice structure, and they suggest that favorable intermolecular interactions among adsorbed molecules are consistent with hydrophobically dominated protein-surface interactions.
扫描隧道显微镜（STM）已被用于直接观察石墨表面的溶菌酶，以便获取有关蛋白质吸附所涉及分子事件的机理信息。实验是在蛋白质水溶液中使用绝缘探针进行的，这样可以跟踪吸附过程的时间进程，包括有序阵列的演变。观察到了蛋白质分子的有序阵列，其晶格间距随本体蛋白质浓度和盐浓度而变化。使用傅里叶分析来确定阵列的平均晶胞尺寸。根据观察到的晶格间距，可以估计蛋白质的表面覆盖率，因此，通过改变条件，可以获得吸附等温线。这些等温线与在疏水表面上使用全内反射荧光（TIRF）光谱测量的吸附等温线相当吻合。由于蛋白质带电且电解质对等温线有影响，静电作用可能是一个控制因素。因此，使用分子静电计算来研究晶格结构的可能起源，结果表明吸附分子之间有利的分子间相互作用与疏水主导的蛋白质-表面相互作用是一致的。
