title: A nickel superoxide dismutase maquette that reproduces the spectroscopic and functional properties of the metalloenzyme.
abstract: Described herein is a nickel superoxide dismutase (NiSOD) maquette ([Ni(SOD(M1))]) based on the first 12 residues from the N-terminal sequence of Streptomyces coelicolor NiSOD. The apopeptide (SOD(M1)) was prepared by standard solid-phase Fmoc peptide synthesis. SOD(M1) will readily coordinate Ni(II) in a 1:1 ratio in slightly basic aqueous sodium phosphate buffer (0.1 M; pH = 7.2) forming a lightly colored beige/pink solution. Unlike NiSOD, which is isolated as a 1:1 mixture of oxidized (Ni(III)) and reduced (Ni(II)) forms, [Ni(SOD(M1))] can only be isolated in the Ni(II) oxidation state. The UV/vis, X-ray absorption, and CD spectra of [Ni(II)(SOD(M1))] correspond well with those reported for the reduced form of NiSOD. Despite the fact that [Ni(III)(SOD(M1))] is not isolable, [Ni(SOD(M1))] has an appropriate redox potential to act as an SOD (E(1/2) = 0.70(2) V vs Ag/AgCl) and in fact will catalytically disproportionate >40 000 equiv of KO(2).
authors.affiliation: Department of Chemistry, University of Nevada, Reno, Reno, Nevada 89557, USA. shearer@chem.unr.edu
authors.forename: Jason
authors.initials: J
authors.lastname: Shearer
authors.forename: Linh M
authors.initials: LM
authors.lastname: Long
mesh_terms: D002384:Catalysis; D008956:Models, Chemical; D009532:Nickel / Q000737:chemistry*; D010084:Oxidation-Reduction; D011487:Protein Conformation; D013052:Spectrometry, X-Ray Emission; D013056:Spectrophotometry, Ultraviolet; D048372:Streptomyces coelicolor / Q000201:enzymology*; D013482:Superoxide Dismutase / Q000737:chemistry / Q000378:metabolism
chemical_list: D009532:Nickel; D013482:Superoxide Dismutase