The type 1 copper site of pseudoazurin: axial and rhombic

J Inorg Biochem. 2014 Aug:137:57-63. doi: 10.1016/j.jinorgbio.2014.03.016. Epub 2014 Apr 12.

Abstract

We report on a high-frequency electron-paramagnetic-resonance study of the type 1 copper site of pseudoazurin. The spectra fully resolve the contribution of a nearly axial spectrum besides the rhombic spectrum, which unequivocally proves the existence of two conformations of the copper site. Pseudoazurins have been considered from Achromobacter cycloclastes including eight mutants and from Alcaligenes faecalis. The two conformations are virtually the same for all pseudoazurins, but the rhombic/axial population varies largely, between 91/9 and 33/67. These observations are discussed in relation to optical absorption spectra and X-ray diffraction structures. A similar observation for fern plastocyanin from Dryopteris crassirhizoma suggests that dual conformations of type 1 copper sites are more common.

Keywords: 275GHz EPR; Absorption spectrum; Blue copper sites; Plastocyanin; Pseudoazurin; Type 1 copper.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Achromobacter cycloclastes / chemistry
  • Alcaligenes faecalis / chemistry
  • Azurin / chemistry*
  • Azurin / metabolism
  • Binding Sites
  • Copper / chemistry*
  • Electron Spin Resonance Spectroscopy
  • Plastocyanin / chemistry*
  • Plastocyanin / metabolism
  • Protein Conformation*
  • Spectrum Analysis, Raman
  • X-Ray Diffraction

Substances

  • pseudoazurin
  • Azurin
  • Copper
  • Plastocyanin