Verma Ayush, Simard Joseph M, Rotello Vincent M
Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, USA.
Langmuir. 2004 May 11;20(10):4178-81. doi: 10.1021/la036183v.
Negatively charged carboxylate-functionalized mixed monolayer protected clusters (MMPCs) effectively bind and inhibit alpha-chymotrypsin based on complementary electrostatic surface recognition. We demonstrate that this binding can be disrupted by varying the ionic strength of the medium. Enzyme activity in the presence of MMPCs increases from 5% to 97% of native activity as salt concentration is increased from 0 to 1.5 M. Variation of ionic strengths after complete binding over 13 h results only in a modest restoration of enzymatic activity (< 35%). The conformation of chymotrypsin was characterized using circular dichroism and fluorescence spectroscopy, correlating structure with enzymatic activity. This work provides a useful insight of the electrostatic influence on protein--MMPC interactions and can be applied toward MMPC-based controlled release of proteins in vivo.
带负电荷的羧酸盐功能化混合单层保护簇（MMPCs）基于互补的静电表面识别有效地结合并抑制α-糜蛋白酶。我们证明这种结合可以通过改变介质的离子强度来破坏。随着盐浓度从0增加到1.5 M，MMPCs存在下的酶活性从天然活性的5%增加到97%。在完全结合13小时后改变离子强度仅导致酶活性适度恢复（<35%）。使用圆二色性和荧光光谱对糜蛋白酶的构象进行了表征，将结构与酶活性相关联。这项工作为静电对蛋白质-MMPC相互作用的影响提供了有用的见解，并可应用于基于MMPC的体内蛋白质控释。
