Determination of the surface potential of two-dimensional crystals of bacteriorhodopsin by AFM

被引:13
作者
Hartley, P
Matsumoto, M
Mulvaney, P [1 ]
机构
[1] Univ Melbourne, Sch Chem, Adv Mineral Prod Res Ctr, Parkville, Vic 3052, Australia
[2] Kyoto Univ, Inst Chem Res, Uji, Kyoto 611, Japan
关键词
D O I
10.1021/la980079+
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
The interaction forces between a silica sphere and two-dimensional bacteriorhodopsin crystals (bR) were measured in NaNO3 solutions at different pH values, and at two electrolyte concentrations. Using the known zeta potential for the silica sphere as a function of pH, the surface potential of the bR crystals could be determined. The isoelectric point (iep) was found to be pH 4.3 +/- 0.5. The crystals had a uniform thickness on substrates of 5.2 +/- 0.5 nm, and the Hamaker constant for the bR-H2O-SiO2 system was estimated to be 0.5-1.0 x 10(-20) J at pH values near the iep. Analysis of the force curves suggested that the surface charge on the protein surface remained constant during approach of the silica colloid probe.
引用
收藏
页码:5203 / 5209
页数:7
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