You Chang-Cheng, De Mrinmoy, Han Gang, Rotello Vincent M
Department of Chemistry, University of Massachusetts, 710 North Pleasant Street, Amherst, Massachusetts 01003, USA.
J Am Chem Soc. 2005 Sep 21;127(37):12873-81. doi: 10.1021/ja0512881.
Water-soluble gold nanoparticles bearing diverse l-amino acid terminals have been fabricated to probe the effect of receptor surface on protein surface binding. The interaction of these nanoparticles with alpha-chymotrypsin (ChT) was investigated by activity assay, gel electrophoresis, zeta-potential, circular dichroism, and fluorescence spectroscopy. The results show that both electrostatic and hydrophobic interactions between the hydrophobic patches of receptors and the protein contribute to the stability of the complex. The microscopic binding constants for these receptor-protein systems are 10(6)-10(7) M(-1), with the capacity of the nanoparticle receptors to bind proteins determined by both their surface area and their surface charge density. Furthermore, it is found that the hydrophilic side chains destabilize the ChT structure through either competitive hydrogen bonding or breakage of salt bridges, whereas denaturation was much slower with hydrophobic amino acid side chains. Significantly, correlation between the hydrophobicity index of amino acid side chains and the binding affinity and denaturation rates was observed.
已制备出带有不同L-氨基酸末端的水溶性金纳米颗粒，以探究受体表面对蛋白质表面结合的影响。通过活性测定、凝胶电泳、zeta电位、圆二色性和荧光光谱研究了这些纳米颗粒与α-胰凝乳蛋白酶（ChT）的相互作用。结果表明，受体的疏水区域与蛋白质之间的静电和疏水相互作用都有助于复合物的稳定性。这些受体-蛋白质系统的微观结合常数为10(6)-10(7) M(-1)，纳米颗粒受体结合蛋白质的能力由其表面积和表面电荷密度共同决定。此外，发现亲水性侧链通过竞争性氢键或盐桥断裂使ChT结构不稳定，而疏水性氨基酸侧链导致的变性则要慢得多。值得注意的是，观察到氨基酸侧链的疏水指数与结合亲和力和变性速率之间存在相关性。
