Regulation of Thrombin Activity with Ultrasmall Nanoparticles: Effects of Surface Chemistry.

Nanomaterials displaying well-tailored sizes and surface chemistries can provide novel ways with which to modulate the structure and function of enzymes. Recently, we showed that gold nanoparticles (AuNPs) in the ultrasmall size regime could perform as allosteric effectors inducing partial inhibition of thrombin activity. We now find that the nature of the AuNP surface chemistry controls the interactions to the anion-binding exosites 1 and 2 on the surface of thrombin, the allosterically induced changes to the active-site conformation, and, by extension, the enzymatic activity. Ultrasmall AuNPs passivated with