Allosteric inhibition of a-thrombin enzymatic activity with ultrasmall gold nanoparticles
Data
2018-09-24
Autores
Lira, André 
Ferreira, Rodrigo
Torquato, Ricardo
Oliva, Maria L.V.
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The catalytic activity of enzymes can be regulated by interactions with synthetic nanoparticles (NPs) in
a number of ways. To date, however, the potential use of NPs as allosteric effectors has not been
investigated in detail. Importantly, targeting allosteric (distal) sites on the enzyme surface could afford
unique ways to modulate the activity, allowing for either enzyme activation, partial or full inhibition.
Using p-mercaptobenzoic acid-coated ultrasmall gold NPs (AuMBA) and human a-thrombin as a model
system, here we experimentally tested the hypothesis that enzyme activity could be regulated through
ultrasmall NP interactions at allosteric sites. We show that AuMBA interacted selectively and reversibly
around two positively charged regions of the thrombin surface (exosites 1 and 2) and away from the
active site. NP complexation at the exosites transmitted long-range structural changes over to the active
site, altering both substrate binding affinity and catalysis. Significantly, thrombin activity was partially
reduced – but not completely inhibited – by interactions with AuMBA. These findings indicate that
interactions of proteins with ultrasmall NPs may mimic a typical biomolecular complexation event, and
suggest the prospect of using ultrasmall particles as synthetic receptors to allosterically regulate protein
function