Reactions gold-protein

These bis(thiolato)gold(I) complexes are useful models for providing insights into the chemistry of the end products of the reactions between 1 1 gold thiolates and any excess (including other) thiol, including some reactions with proteins in vivo. 

Figure 1 (A) Schematic section through a chemically microstructured TSG sample after pCP with reactive DSU, formation of a HUT SAM and immobilization of proteins. Primary amines of proteins react with the end groups of the DSU crosslinker (11, ll -dithio-bis(succinimi-dylundecanoate), Fig. 1C bound DSU (thiolate form) with the formation of an amide bond. (B) Schematic section through a microstructured silicon/gold structure after pCP, etching the gold, titanium and silicon, removal of the etch-resistant monolayer, formation of a reactive monolayer and finally reaction with protein.

These gold exchange reactions are prevented by prior alkylation of this protein thiol. Because of its lower affinity for gold when Cys-34 exists as a disulfide species, gold-to-sulfhydryl and gold-to-total albumin ratios are considered when analyzing data. Albumin with the Cys-34 blocked by alkylation is often used. 

Shaw, C.F. Ill, Coffer, M.T., Klingbed, J. and Mirabelli, C.K. (1988) Application of phosphorus-31 NMR chemical shift gold afiinity correlation to hemoglobin-gold binding and the first inter-protein gold transfer reaction. Journal of the American Chemical Society, 110, 729-734. 

Figure 17.15 The small carboxylate-alkyne compound 4-pentynoic acid can be used to modify proteins at their amine groups with EDC to provide alkyne sites for click chemistry-mediated conjugation. The subsequent reaction of an azido-PEG-modified gold nanoparticle with the alkynyl-protein in the presence of Cu1+ yields the triazole-coupled protein.

M. Vladimir, M. Mirsky, O. Riepl, and O. Wolfbeis, Capacitive monitoring of protein immobilization and antigen—antibody reactions on monomolecular alkylthiol films on gold electrodes. Biosens. Bioelectron. 12, 977-989 (1997). 

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