Metal sites of copper-zinc superoxide dismutase.

Published

Journal Article

Silver-copper and silver-cobalt proteins have been prepared in which Ag+ resides in the native copper site of superoxide dismutase and either Cu2+ of Co2+ reside in the zinc site. The electron paramagnetic resonance (EPR) spectrum of the copper and the visible absorption spectrum of the cobalt greatly resemble those of either Cu4 of Cu2,Cu2,Co2 proteins, respectively, in which the copper of the native copper sites has been reduced. It was found that, unlike cyanide, azide anion would not perturb the EPR spectrum of Ag2,Cu2 protein. Since azide produces the same perturbation upon the EPR spectrum of native and Cu2 proteins, it must bind to the copper and not the zinc of superoxide dismutase. A model of the metal sites of the enzyme has been fitted to a 3-A electron-density map using an interactive molecular graphics display. The model shows that histidine-61, which appears to bind both copper and zinc, does not lie in the plane of the copper and its three other histidine ligands, but occupies a position intermediate between planar and axial. This feature probably accounts for the rhombicity of the EPR spectrum and the activity of the enzyme.

Full Text

Duke Authors

Cited Authors

  • Beem, KM; Richardson, DC; Rajagopalan, KV

Published Date

  • May 3, 1977

Published In

Volume / Issue

  • 16 / 9

Start / End Page

  • 1930 - 1936

PubMed ID

  • 192282

Pubmed Central ID

  • 192282

International Standard Serial Number (ISSN)

  • 0006-2960

Digital Object Identifier (DOI)

  • 10.1021/bi00628a027

Language

  • eng

Conference Location

  • United States