Novel tripeptide model of nickel superoxide dismutase.
Inorg Chem
; 49(2): 362-4, 2010 Jan 18.
Article
em En
| MEDLINE
| ID: mdl-20000358
Nickel superoxide dismutase (Ni-SOD) catalyzes the disproportionation of superoxide to molecular oxygen and hydrogen peroxide, but the overall reaction mechanism has yet to be determined. Peptide-based models of the 2N:2S nickel coordination sphere of Ni-SOD have provided some insight into the mechanism of this enzyme. Here we show that the coordination sphere of Ni-SOD can be mimicked using the tripeptide asparagine-cysteine-cysteine (NCC). NCC binds nickel with extremely high affinity at physiological pH with 2N:2S geometry, as demonstrated by electronic absorption and circular dichroism (CD) data. Like Ni-SOD, Ni-NCC has mixed amine/amide ligation that favors metal-based oxidation over ligand-based oxidation. Electronic absorption, CD, and magnetic CD (MCD) data collected for Ni-NCC are consistent with a diamagnetic Ni(II) center bound in square-planar geometry. Ni-NCC is quasi-reversibly oxidized with a midpoint potential of 0.72(2) V (vs Ag/AgCl) and breaks down superoxide in an enzyme-based assay, supporting its potential use as a model for Ni-SOD chemistry.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Oligopeptídeos
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Superóxido Dismutase
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Biomimética
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Níquel
Idioma:
En
Ano de publicação:
2010
Tipo de documento:
Article