Scripps VIVO scripps research logo

  • Index
  • Log in
  • Home
  • People
  • Organizations
  • Research
  • Events
Search form

Coupled redox potentials in manganese and iron superoxide dismutases from reaction kinetics and density functional/electrostatics calculations

Academic Article
uri icon
  • Overview
  • Identity
  • Additional Document Info
  • View All
scroll to property group menus

Overview

authors

  • Han, W. G.
  • Lovell, T.
  • Noodleman, Louis

publication date

  • January 2002

journal

  • Inorganic Chemistry  Journal

abstract

  • A methodology for determining the coupled redox potentials (DeltaE(redox) degrees (coupled)) of manganese and iron superoxide dismutases (Mn(Fe)SODs), from the standard redox potential of reaction (O(2)(-) + 2H(+) + e(-) --> H(2)O(2)) and the experimental kinetic rate constants of Mn(Fe)SOD proteins, has been presented for the first time. A combined density functional (DF) and electrostatic protein/reaction field (DF/electrostatics) model has also been applied to seven protein structures, to study the structural, energetic, simple redox potential, pK(a), and coupled redox potential properties associated with each active site. The quantum cluster active site models, which include the metal, first shell ligands, represented by amino acid side chains and a solvent derived ligand, and the second shell H-bonding partners, were taken from the crystal structures, and geometry was optimized in four kinds of states: oxidized (III) and reduced (II) states with either a H(2)O molecule or a OH(-) group as the fifth coordinated ligand. We conclude from the calculations that the oxidized and reduced Mn(Fe)SODs are in the Mn(3+)(Fe(3+))(OH(-)) and Mn(2+)(Fe(2+))(H(2)O) forms, respectively; proton transfers will happen in both steps of the dismutation of superoxide anion (O(2)(-)), and the proton-transfer reactions will occur prior to or concerted with the electron transfer from O(2)(-) group to the Mn(3+)(Fe(3+))SOD metal center. The DeltaE(redox) degrees (coupled) of E. coli FeSOD calculated by the DF/electrostatics method is 0.16 V, which is very close to the experimental value of 0.25 V. The absolute values of DeltaE(redox) degrees (coupled) for T. thermophilus, human wild-type, and mutant Q143N MnSODs obtained from the DF/electrostatics method are -0.25, -0.29, and -0.11 V, which present the same trend and very similar relative values to those obtained from experimental kinetic rate constants (0.40, 0.32, and 0.59 V, respectively). The order DeltaE(redox) degrees (human wild-type) < DeltaE(redox) degrees (T. thermophilus) < DeltaE(redox) degrees (E. coli) < DeltaE(redox) degrees (Q143N) for MnSOD proteins is predicted by the DF/electrostatics calculations.

subject areas

  • Binding Sites
  • Catalysis
  • Crystallography, X-Ray
  • Escherichia coli
  • Humans
  • Iron
  • Kinetics
  • Manganese
  • Models, Chemical
  • Molecular Structure
  • Oxidation-Reduction
  • Protein Conformation
  • Superoxide Dismutase
  • Thermus thermophilus
scroll to property group menus

Identity

International Standard Serial Number (ISSN)

  • 0020-1669

Digital Object Identifier (DOI)

  • 10.1021/ic010355z

PubMed ID

  • 11800609
scroll to property group menus

Additional Document Info

start page

  • 205

end page

  • 218

volume

  • 41

issue

  • 2

©2021 The Scripps Research Institute | Terms of Use | Powered by VIVO

  • About
  • Contact Us
  • Support