The engineered silver nanoparticles (AgNPs) undergo profound chemical transformations in biological systems. Amongst the chemicals that alter AgNPs are proteins, which can form a protein corona to coat the NPs, alter aggregation states to influence AgNP bioavailability, and/or catalyze dissolution to change the biological transport and biological fate of AgNPs. Although recent studies have explored the importance of many blood proteins within protein coronas, less is known about the interactions of AgNPs with common metalloproteins like Zn fingers. Zinc fingers possess a combination of cysteine and histidine residues that bind Zn(II) as a structural element. While both silver and zinc have high affinity for cysteine and histidine coordination based on the HSAB theory and Zn (II) binding has been well-characterized, the binding of silver species to zinc finger domains is less understood. Using a small library of Zn finger peptides, we aim to evaluate the impact of AgNPs on Zn finger structure and function. Titrations of Zn fingers with Ag (I) using UV-Vis spectroscopy show displacement Zn (II) from the Zn(II) bound peptides. Electrospray ionization mass spectroscopy analysis of the Zn fingers with Ag (I) and AgNP confirm formation of Ag(I) bound peptides. Our initial circular dichroism studies on both CP-CCHC and NCp7 show that the conformations of the Ag(I) and AgNP-bound complexes differ from those of the Zn(II) species.The results show that for the Zn finger peptides studied here, Ag(I)(aq) and AgNPs are likely to displace the native Zn, suggesting that Ag(I) and AgNPs might be relevant in the context of AgNP biochemical response.

Characterization of silver (I) and engineered Silver Nanoparticle (AgNP) binding to apo and metal reconstituted zinc finger peptides

253rd National Meeting (2017)

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