Kinetics of integrated electron transfer in the mitochondrial respiratory chain: random collisions vs. solid state electron channeling

Abstract

Recent evidence, mainly based on native electrophoresis, has suggested that the mitochondrial respiratory chain is organized in the form of supercomplexes, due to the aggregation of the main respiratory chain enzymatic complexes. This evidence strongly contrasts the previously accepted model, the Random Diffusion Model, largely based on kinetic studies, stating that the complexes are randomly distributed in the lipid bilayer of the inner membrane and functionally connected by lateral diffusion of small redox molecules, i.e., coenzyme Q and cytochrome c. This review critically examines the experimental evidence, both structural and functional, pertaining to the two models and attempts to provide an updated view of the organization of the respiratory chain and of its kinetic consequences. The conclusion that structural respiratory assemblies exist is overwhelming, whereas the expected functional consequence of substrate channeling between the assembled enzymes is controversial. Examination of the available evidence suggests that, although the supercomplexes are structurally stable, their kinetic competence in substrate channeling is more labile and may depend on the system under investigation and the assay conditions.

Fluconazole Assists Berberine To Kill Fluconazole-Resistant Candida albicans

“…Interestingly, the microarray results showed that the expression of energy metabolism-related genes, including COX9, orf19.4727, GPM2, QCR7, orf19.2067, GIT2, LSC1, and HXT5, changed significantly. COX9, orf19.4727, QCR7, and LSC1 encode a putative subunit VIIa of cytochrome c oxidase, succinate dehy- drogenase, ubiquinol-cytochrome c reductase, and succinate coenzyme A (succinate-CoA) ligase subunit, respectively, and all of them play roles in electron transfer in the mitochondrial respiratory chain (41). GPM2 encodes putative phosphoglycerate mutase, which is involved in glycolysis (42).…”

Regulation of oxidative phosphorylation through parallel activation

“…For instance Halestrap proposed that changes in mitochondria volume and thus protein density serve as the regulatory factor [112]. Another possibility is an association of respiratory complexes in supercomplexes [113,114].…”

Mitochondrial Respiratory Supercomplex Association Limits Production of Reactive Oxygen Species from Complex I

“…Available evidence arguing in favor or against substrate channeling has been critically reviewed in previous articles by the authors (42,45). In brief, reconstitution studies (37) showed that electron transfer be-…”