engleski

Thiol vs. disulphide: a DFT study of the nano-bio interface

The increasing number of potential applications of silver and gold nanoparticles in medicine brings about the need to elucidate their interactions with the biological system. Adsorption of proteins to the nanoparticle surface is particularly important as it changes their identity and impacts their behaviour and fate in biological matrices.1 Considering high affinity of sulphur for metals, special emphasis should be given to the role of thiol residues in nano-bio interactions, 2 although cysteine residues in proteins and peptides often form disulphide bonds.3 This study aims to explore the difference in the reactions of free thiols and disulphides with silver and gold by computational approach. Cysteine and cystine are used as representatives of thiol and disulphide-containing molecules. Both molecules were placed in the vicinity of neutral and cationic silver and gold clusters in several orientations, to explore the potential energy surface and to identify most stable structures. All calculations were performed in Gaussian 16 software, on the B3LYP level of theory with LANL2DZ basis set. Computations demonstrated that cationic metal clusters formed stable complexes with deprotonated thiols, while they preferred to interact with carboxyl group in protonated cysteine and cystine. Neutral clusters coordinated to both thiols and disulphides, but the latter structures were less stable. The displayed tendency of metals to induce the disulphide bonds cleavage was the most significant result, highlighting further mechanistic research on interaction between nanoparticles and proteins. These findings, combined with experimental work, will provide important contributions towards understanding of the nano-bio interface.

cysteine, cistine, silver, gold, DFT

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