| Abstract
| - Water-soluble gold nanoparticles bearing diverse l-amino acid terminals have been fabricatedto probe the effect of receptor surface on protein surface binding. The interaction of these nanoparticleswith α-chymotrypsin (ChT) was investigated by activity assay, gel electrophoresis, zeta-potential, circulardichroism, and fluorescence spectroscopy. The results show that both electrostatic and hydrophobicinteractions between the hydrophobic patches of receptors and the protein contribute to the stability of thecomplex. The microscopic binding constants for these receptor−protein systems are 106−107 M-1, withthe capacity of the nanoparticle receptors to bind proteins determined by both their surface area and theirsurface charge density. Furthermore, it is found that the hydrophilic side chains destabilize the ChT structurethrough either competitive hydrogen bonding or breakage of salt bridges, whereas denaturation was muchslower with hydrophobic amino acid side chains. Significantly, correlation between the hydrophobicity indexof amino acid side chains and the binding affinity and denaturation rates was observed.
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