Photoinduced electron-transfer kinetics of singly labeled ruthenium bis(bipyridine) dicarboxybipyridine cytochrome c derivatives

Biochemistry. 1989 Oct 17;28(21):8659-65. doi: 10.1021/bi00447a057.

Abstract

Cytochrome c derivatives labeled at specific lysine amino groups with ruthenium bis(bipyridine) dicarboxybipyridine [RuII(bpy)2(dcbpy)] were prepared by using the procedure described previously [Pan, L. P., Durham, B., Wolinska, J., & Millett, F. (1988) Biochemistry 27, 7180-7184]. Four additional singly labeled derivatives were purified, bringing the total number to 10. These derivatives have a strong luminescence emission centered at 662 nm arising from the excited state, RuII*. Transient absorption spectroscopy was used to directly measure the rate constants for the photoinduced electron-transfer reaction from RuII* to the ferric heme group (k1) and for the thermal back-reaction from the ferrous heme group to RuIII (k2). The rate constants were found to be k1 = 14 X 10(6) s-1 and k2 = 24 X 10(6) s-1 for the derivative modified at lysine 72, which has a distance of 8-16 A between the ruthenium and heme groups. Similar rate constants were found for the derivatives modified at lysines 13 and 27, which have distances of 6-12 A separating the ruthenium and heme groups. The rate constants were significantly slower for the derivatives modified at lysine 25 (k1 = 1 X 10(6) s-1, k2 = 1.5 X 10(6) s-1) and lysine 7 (k1 = 0.3 X 10(6) s-1, k2 = 0.5 X 10(6) s-1), which have distances of 9-16 A. Transients due to photoinduced electron transfer could not be detected for the remaining derivatives, which have larger distances between the ruthenium and heme groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • 2,2'-Dipyridyl / analogs & derivatives
  • 2,2'-Dipyridyl / metabolism*
  • Animals
  • Chemical Phenomena
  • Chemistry
  • Chromatography
  • Cytochrome c Group / metabolism*
  • Electron Transport
  • Horses
  • Kinetics
  • Light
  • Organometallic Compounds*
  • Pyridines / metabolism*
  • Ruthenium
  • Spectrum Analysis

Substances

  • Cytochrome c Group
  • Organometallic Compounds
  • Pyridines
  • 2,2'-Dipyridyl
  • ruthenium bis(bipyridine)dicarboxybipyridine
  • Ruthenium