Model studies of the histidine-tyrosine cross-link in cytochrome C oxidase reveal the flexible substituent effect of the imidazole moiety

Org Lett. 2005 Jun 23;7(13):2735-8. doi: 10.1021/ol050916g.

Abstract

[reaction: see text] Experimental and theoretical studies were carried out to interrogate the effect of an imidazole substituent in each of the ortho, meta, and para positions on the pK(a), E degrees , and O-H BDE of phenol. The results reveal that imidazole substitution lowers the pK(a) of phenol and increases the E degrees of phenoxide due to its sigma-electron withdrawing ability (sigma(p)(-) = +0.21, sigma(m)(-) = +0.45) but decreases the O-H BDE and E degrees of phenol due to its pi-electron-donating ability (sigma(p)(+) = -0.45).

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Electron Transport Complex IV / chemistry*
  • Electron Transport Complex IV / metabolism
  • Histidine / chemistry
  • Imidazoles / chemistry
  • Imidazoles / pharmacokinetics*
  • Models, Theoretical*
  • Molecular Conformation
  • Molecular Structure
  • Oxidation-Reduction
  • Structure-Activity Relationship
  • Tyrosine / chemistry

Substances

  • Imidazoles
  • Tyrosine
  • Histidine
  • imidazole
  • Electron Transport Complex IV