You Chang-Cheng, Agasti Sarit S, De Mrinmoy, Knapp Michael J, Rotello Vincent M
Department of Chemistry, University of Massachusetts, 710 North Pleasant Street, Amherst, Massachusetts 01003, USA.
J Am Chem Soc. 2006 Nov 15;128(45):14612-8. doi: 10.1021/ja064433z.
Amino-acid-functionalized gold clusters modulate the catalytic behavior of alpha-chymotrypsin (ChT) toward cationic, neutral, and anionic substrates. Kinetic studies reveal that the substrate specificity (k(cat)/K(M)) of ChT-nanoparticle complexes increases by approximately 3-fold for the cationic substrate but decreases by 95% for the anionic substrate as compared with that of free ChT, providing enhanced substrate selectivity. Concurrently, the catalytic constants (k(cat)) of ChT show slight augmentation for the cationic substrate and significant attenuation for the anionic substrate in the presence of amino-acid-functionalized nanoparticles. The amino acid monolayer on the nanoparticle is proposed to control both the capture of substrate by the active site and release of product through electrostatic interactions, leading to the observed substrate specificities and catalytic constants.
氨基酸功能化金簇调节α-胰凝乳蛋白酶（ChT）对阳离子、中性和阴离子底物的催化行为。动力学研究表明，与游离ChT相比，ChT-纳米颗粒复合物对阳离子底物的底物特异性（k(cat)/K(M)）增加了约3倍，而对阴离子底物则降低了95%，从而提高了底物选择性。同时，在存在氨基酸功能化纳米颗粒的情况下，ChT的催化常数（k(cat)）对阳离子底物略有增加，对阴离子底物则显著衰减。纳米颗粒上的氨基酸单层被认为通过静电相互作用控制活性位点对底物的捕获和产物的释放，从而导致观察到的底物特异性和催化常数。
