Tunable Inhibition and Denaturation of α-Chymotrypsin with Amino Acid-Functionalized Gold Nanoparticles

Abstract

Water-soluble gold nanoparticles bearing diverse l-amino acid terminals have been fabricated to probe the effect of receptor surface on protein surface binding. The interaction of these nanoparticles with alpha-chymotrypsin (ChT) was investigated by activity assay, gel electrophoresis, zeta-potential, circular dichroism, and fluorescence spectroscopy. The results show that both electrostatic and hydrophobic interactions between the hydrophobic patches of receptors and the protein contribute to the stability of the complex. The microscopic binding constants for these receptor-protein systems are 10(6)-10(7) M(-1), with the capacity of the nanoparticle receptors to bind proteins determined by both their surface area and their surface charge density. Furthermore, it is found that the hydrophilic side chains destabilize the ChT structure through either competitive hydrogen bonding or breakage of salt bridges, whereas denaturation was much slower with hydrophobic amino acid side chains. Significantly, correlation between the hydrophobicity index of amino acid side chains and the binding affinity and denaturation rates was observed.

Gold nanoparticles as a platform for creating a multivalent poly-SUMO chain inhibitor that also augments ionizing radiation

“…2C) (23). Derivative 2 or 3 was equilibrated with C4-AuNP in dichloromethane for 4 d, according to published procedures (24). The precipitated ligand-AuNP conjugate 4 or 5 was collected via filtration.…”

“…The negative control, 3, was constructed in a similar manner as 2 with 2-chlorotrityl resin loaded with Fmoc-Gly-OH, Fmoc -7-aminoheptanoic acid and 3-(t-butoxycarbonylthio) propanioc acid. The AuNP-ligand conjugate was synthesized according to a procedure described previously (36). To conjugate a small amount of biotin onto AuNP 4 or 5, C4-AuNP (6 mg) was combined with derivative 2 (10 mg) or 3 (8 mg) and thiol-biotin (2 mg; Nanoscience Instruments, CMT015).…”

Peptide‐Capped Gold Nanoparticles: Towards Artificial Proteins

“…Rotello's group has addressed these two points in a series of recent papers, first looking at the release of thiolated ligands in the presence of the glutathione peptide (present at millimolar concentration inside living cells); [26,27] then looking at the denaturation and inactivation of chymotrypsin by gold nanoparticles capped with alkane-thiol ligands eventually terminated with amino acids. [28,29] The latter studies provided fundamental insights into peptide-capped nanoparticle interactions with proteins; for example, demonstrating that hydrophobic amino acid side chains present on a nanoparticle surface can contribute to the stabilization of an adsorbed protein. Wang et al demonstrated the preparation of DNA, biotinylated, and bifunctional peptidecapped gold nanoparticles using mixed peptide monolayers composed of CALNN, CALNNGKbiotinG, and a CALNN-DNA conjugate.…”

Affinity Polymers Tailored for the Protein A Binding Site of Immunoglobulin G Proteins

“…[14,15] Finally, gold nanoparticles functionalized with amino acids have been introduced for protein binding and concomitant denaturation. [16][17][18][19] Deliberate and specific interference with synthetic agents, however, has been coined as "high-hanging fruit in drug discovery", [20] and few examples exist that do not rely on library screens. [21][22][23] Several molecular imprinting technologies have been tried on proteins but still suffer from low non-imprinted polymer/molecularly imprinted polymer (NIP/MIP) ratios and incomplete protein recovery; the most promising techniques involve epitope imprinting (most often restricted to N/C termini), hierarchical imprinting, and imprinted soft nanoparticles.…”