Skepö Marie, Linse Per, Arnebrant Thomas
Health and Society, Malmö University, S-205 06 Malmö, Sweden.
J Phys Chem B. 2006 Jun 22;110(24):12141-8. doi: 10.1021/jp056033o.
Structural properties of the acidic proline rich protein PRP-1 of salivary origin in bulk solution and adsorbed onto a negatively charged surface have been studied by Monte Carlo simulations. A simple model system with focus on electrostatic interactions and short-ranged attractions among the uncharged amino acids has been used. In addition to PRP-1, some mutants were considered to assess the role of the interactions in the systems. Contrary to polyelectrolytes, the protein has a compact structure in salt-free bulk solutions, whereas at high salt concentration the protein becomes more extended. The protein adsorbs to a negatively charged surface, although its net charge is negative. The adsorbed protein displays an extended structure, which becomes more compact upon addition of salt. Hence, the conformational response upon salt addition in the adsorbed state is the opposite as compared to that in bulk solution. The conformational behavior of PRP-1 in bulk solution and at charged surfaces as well as its propensity to adsorb to surfaces with the same net charge are rationalized by the block polyampholytic character of the protein. The presence of a triad of positively charged amino acids in the C-terminal was found to be important for the adsorption of the protein.
通过蒙特卡罗模拟研究了唾液来源的富含酸性脯氨酸蛋白PRP-1在本体溶液中以及吸附到带负电表面后的结构特性。使用了一个简单的模型系统，重点关注静电相互作用以及不带电氨基酸之间的短程吸引力。除了PRP-1，还考虑了一些突变体来评估系统中相互作用的作用。与聚电解质相反，该蛋白在无盐本体溶液中具有紧密结构，而在高盐浓度下蛋白会变得更加伸展。该蛋白会吸附到带负电的表面，尽管其净电荷为负。吸附的蛋白呈现伸展结构，加盐后会变得更加紧密。因此，与本体溶液相比，吸附状态下加盐后的构象响应是相反的。PRP-1在本体溶液和带电表面的构象行为以及其吸附到具有相同净电荷表面的倾向可通过该蛋白的嵌段聚两性电解质特性来解释。发现C端存在一组带正电的氨基酸对该蛋白的吸附很重要。
