Modulation of enzyme substrate selectivity using tetraethylene glycol functionalized gold nanoparticles

摘要

Tetraethylene glycol (TEG) functionalized gold nanoparticles with 2 nm core diameters(AuTEG) enhance α-chymotrypsin (ChT) enzyme activity in a substrate-selective fashion. Weexplored the hydrolysis of four different substrates and observed a marked increase in activitywith the most hydrophobic substrate N-succinyl-alanine-alanine-proline-phenylalanine-p-nitroanilide (TP), while the othersubstrates remain virtually unaffected by the AuTEG 'crowding effect' in solution. Theenhancement in catalysis is indicated by an increase in K_(cat)/ K_mas obtained fromLineweaver–Burk analysis and we hypothesize it to arise from a macromolecular crowdingeffect analogous to that observed with high molecular weight poly(ethylene glycol) (PEG)polymers.