Journal article
Intracomplex electron transfer between ruthenium-65-cytochrome b5 and position-82 variants of yeast iso-1-cytochrome c
Biochemistry (Easton), v 32(29), pp 7519-7525
27 Jul 1993
PMID: 8393343
Featured in Collection : UN Sustainable Development Goals @ Drexel
Abstract
We tested the idea that the aromatic ring on the invariant residue Phe-82 in cytochrome c acts as an electron-transfer bridge between cytochrome c and cytochrome bs. Ru-65-cyt bs was prepared by labeling the single sulfhydryl group on T65C cytochrome bs with [4-(bromomethyl)-4'-methylbipy-ridine] [bis(bipyridine)] ruthenium2"1" as previously described [Willie, A., Stayton, P. S., Sligar, S. G., Durham,B., & Millett, F. (1992) Biochemistry 31, 7237-7242], Laser excitation of the complex formed betweenRu-65-cyt bs and Saccharomyces cerevisiae iso-1 -cytochrome c at low ionic strength results in rapid electron transfer from the excited-state Ru(II*) to the heme group of Ru-65-cyt bs followed by biphasic electron transfer to the heme group of cytochrome c with rate constants of (1.0 ± 0.2) X 105 s™1 and (2.0 ± 0.4)X 104 s_1. Variants of iso-1 -cytochrome c substituted at Phe-82 with Tyr, Gly, Leu, and lie have fast-phase rate constants of 0.4, 1.9, 2.1, and 2.0 X 105 s_1 and slow-phase rate constants of 5.3, 3.5, 2.4, and 2.0 X103 s_1, respectively. Increasing the ionic strength to 50 mM results in single-phase intracomplex electron transfer with rate constants of 3.8, 3.1, 3.0, 5.0, and 4.5 X 104 s_1 for the wild-type, Tyr, Gly, Leu, and He variants, respectively. These results demonstrate that an aromatic side chain at residue 82 is not needed for rapid electron transfer with cytochrome bs. Furthermore, two conformational forms of the complex are present at low ionic strength with fast and slow electron-transfer rates. When the ionic strength is increased to 50 mM, interconversion between the two forms of the complex becomes rapid, resulting in a single phase for electron transfer with a rate constant that is intermediate between the slow and fast rates. At still higher ionic strength the complex dissociates, and second-order kinetics are observed
Metrics
Details
- Title
- Intracomplex electron transfer between ruthenium-65-cytochrome b5 and position-82 variants of yeast iso-1-cytochrome c
- Creators
- Anne Willie - University of Arkansas at FayettevilleMark McLean - University of Illinois Urbana-ChampaignRui Qin Liu - University of Arkansas at FayettevilleSharon Hilgen-Willis - University of North Carolina at Chapel HillAleister J SaundersGary J Pielak - University of North Carolina at Chapel HillStephen G Sligar - University of Illinois Urbana-ChampaignBill Durham - University of Arkansas at FayettevilleFrancis Millett - University of Arkansas at Fayetteville
- Publication Details
- Biochemistry (Easton), v 32(29), pp 7519-7525
- Publisher
- American Chemical Society; Washington, DC
- Number of pages
- 7
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Biology
- Web of Science ID
- WOS:A1993LP64300025
- Scopus ID
- 2-s2.0-0027202641
- Other Identifier
- 991021448048104721
UN Sustainable Development Goals (SDGs)
This publication has contributed to the advancement of the following goals:
InCites Highlights
Data related to this publication, from InCites Benchmarking & Analytics tool:
- Collaboration types
- Domestic collaboration
- Web of Science research areas
- Biochemistry & Molecular Biology