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Bioinorganic Chemistry and Applications
Volume 2017 (2017), Article ID 1527247, 7 pages
https://doi.org/10.1155/2017/1527247
Research Article

Co(II) Coordination in Prokaryotic Zinc Finger Domains as Revealed by UV-Vis Spectroscopy

Department of Environmental, Biological and Pharmaceutical Science and Technology, University of Campania-Luigi Vanvitelli, Via Vivaldi 43, 81100 Caserta, Italy

Correspondence should be addressed to Carla Isernia and Gaetano Malgieri

Received 9 August 2017; Revised 3 October 2017; Accepted 16 October 2017; Published 14 December 2017

Academic Editor: Spyros P. Perlepes

Copyright © 2017 Valeria Sivo et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Co(II) electronic configuration allows its use as a spectroscopic probe in UV-Vis experiments to characterize the metal coordination sphere that is an essential component of the functional structure of zinc-binding proteins and to evaluate the metal ion affinities of these proteins. Here, exploiting the capability of the prokaryotic zinc finger to use different combinations of residues to properly coordinate the structural metal ion, we provide the UV-Vis characterization of Co(II) addition to Ros87 and its mutant Ros87_C27D which bears an unusual CysAspHis2 coordination sphere. Zinc finger sites containing only one cysteine have been infrequently characterized. We show for the CysAspHis2 coordination an intense d-d transition band, blue-shifted with respect to the Cys2His2 sphere. These data complemented by NMR and CD data demonstrate that the tetrahedral geometry of the metal site is retained also in the case of a single-cysteine coordination sphere.