Intramolecular oxidation of cytochrome c by covalently attached sulfoaromatic molecules

Biochim Biophys Acta. 1997 Oct 20;1321(3):221-8. doi: 10.1016/s0005-2728(97)00058-3.

Abstract

Two photosensitive molecules, 1-maleimidopyrene-3,6,8-trisulfonate (MPTS) and N-acetylaminoethyl-1-aminonaphthalene-5-sulfonate (AEDANS), are employed to drive the intramolecular oxidation of the heme residue in cytochrome c. Intense pulse illumination (60-120 MW cm-2) of MPTS and AEDANS in the aqueous solution by the third harmonic frequency of Nd-Yag laser drives a two successive-photon process of the dyes. The oxidized products originating from the dyes react with variety of electron donors. MPTS and AEDANS residues were covalently linked the Saccharomyces cerevisiae iso-1-cytochrome c by labeling of its single sulfhydryl group. When pulsed by intensive laser beam the heme of the labeled ferrocytochrome c undergoes fast oxidation. Transient absorption spectroscopy was used to directly measure the rate constants for the photoinduced electron-transfer reaction from the ferros heme group to the oxidized dyes. The rate constant was found to be (3.6 +/- 0.4) x 10(4) s-1 for MPTS derivative. The rate of the heme oxidation in AEDANS derivative was faster than response time of our detection system (20 ns). Rapid photooxidation of cytochrome c makes it a useful tool for fast initiation of electron transfer in oxidized direction within complexes of cytochrome c with the other redox proteins.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arylsulfonates / chemistry
  • Cytochrome c Group*
  • Ferrous Compounds / chemistry
  • Heme / chemistry
  • Kinetics
  • Maleimides / chemistry*
  • Naphthalenesulfonates
  • Oxidation-Reduction
  • Photochemistry
  • Pyrenes / chemistry*
  • Solutions
  • Spectrum Analysis
  • Water

Substances

  • 1-maleimidopyrene-3,6,8-trisulfonate
  • Arylsulfonates
  • Cytochrome c Group
  • Ferrous Compounds
  • Maleimides
  • Naphthalenesulfonates
  • Pyrenes
  • Solutions
  • Water
  • Heme
  • 1,5-AEDANS
  • pyranine