Open AccessRelationship between lateral diffusion, collision frequency, and electron transfer of mitochondrial inner membrane oxidation-reduction components.
Author(s) -
Sharmila Shaila Gupte,
En-Shinn Wu,
Luzia Hoechli,
Mathias Hoechli,
Kenneth A. Jacobson,
Arthur E. Sowers,
Charles R. Hackenbrock
Publication year - 1984
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.81.9.2606
Subject(s) - redox , electron transport chain , diffusion , electron transfer , chemistry , cytochrome c oxidase , chemical physics , cytochrome , electron transport complex iv , biophysics , photochemistry , mitochondrion , inorganic chemistry , biochemistry , thermodynamics , biology , physics , enzyme
Fluorescence recovery after photobleaching was used to determine the diffusion coefficients of the oxidation-reduction (redox) components ubiquinone, complex III (cytochromes b-c1), cytochrome c, and complex IV (cytochrome oxidase) of the mitochondrial inner membrane. All redox components diffuse in two dimensions as common-pool electron carriers. Cytochrome c diffuses in two and three dimensions concomitantly, and its diffusion rate, unlike that of all other redox components, is modulated along with its activity by ionic strength. The diffusion coefficients established in this study reveal that the theoretical diffusion-controlled collision frequencies of all redox components are greater than their experimental maximum (uncoupled) turnover numbers. Since electron transport is slower than the theoretical limit set by the lateral diffusion of the redox components, ordered chains, assemblies, or aggregates of redox components are not necessary to account for electron transport. Rather, mitochondrial electron transport is diffusion coupled, consistent with a "random-collision model" for electron transport.