676270-53-4Relevant academic research and scientific papers
Dipeptide-based models of nickel superoxide dismutase: Solvent effects highlight a critical role to Ni-S bonding and active site stabilization
Gale, Eric M.,Cowart, Darin M.,Scott, Robert A.,Harrop, Todd C.
, p. 10460 - 10471 (2011)
Nickel superoxide dismutase (Ni-SOD) catalyzes the disproportionation of the superoxide radical to O2 and H2O2 utilizing the Ni(III/II) redox couple. The Ni center in Ni-SOD resides in an unusual coordination environment that is distinct from other SODs. In the reduced state (Ni-SODred), Ni(II) is ligated to a primary amine-N from His1, anionic carboxamido-N/thiolato-S from Cys2, and a second thiolato-S from Cys6 to complete a NiN2S2 square-planar coordination motif. Utilizing the dipeptide N2S2- ligand, H 2N-Gly-l-Cys-OMe (GC-OMeH2), an accurate model of the structural and electronic contributions provided by His1 and Cys2 in Ni-SOD red, we constructed the dinuclear sulfur-bridged metallosynthon, [Ni2(GC-OMe)2] (1). From 1 we prepared the following monomeric Ni(II)-N2S2 complexes: K[Ni(GC-OMe)(SC 6H4-p-Cl)] (2), K[Ni(GC-OMe)(StBu)] (3), K[Ni(GC-OMe)(SC6H4-p-OMe)] (4), and K[Ni(GC-OMe)(SNAc)] (5). The design strategy in utilizing GC-OMe2- is analogous to one which we reported before (see Inorg. Chem.2009, 48, 5620 and Inorg. Chem. 2010, 49, 7080) where Ni-SODred active site mimics can be assembled at will with electronically variant RS- ligands. Discussed herein is our initial account pertaining to the aqueous behavior of isolable, small-molecule Ni-SOD model complexes (non-maquette based). Spectroscopic (FTIR, UV-vis, ESI-MS, XAS) and electrochemical (CV) measurements suggest that 2-5 successfully simulate many of the electronic features of Ni-SODred. Furthermore, the aqueous studies reveal a dynamic behavior with regard to RS- lability and bridging interactions, suggesting a stabilizing role brought about by the protein architecture.
