Electron Carriers: Proteins and Cofactors in Oxidative Phosphorylation


Biological electron transfer is mediated by a heterogeneous group of redox cofactors. Most of these compounds are firmly bound by proteins, others migrate freely within membranes, and some are soluble. The orderly flow of electrons through chains of such cofactors is fundamental to the generation of metabolic energy.

Keywords: redox cofactors; electron transfer; oxidative phosphorylation

Figure 1.

Overview of oxidative phosphorylation and photophosphorylation. Electron transfer steps are indicated by thin red arrows, and proton transport by thick red arrows. Dashed red arrows indicate transfer by mobile carriers. (a) Scheme of the respiratory chain; UQ/ UQH2, ubiquinone/‐ol; ETF, electron transfer flavoprotein; c, cytochrome c. (b) Scheme of photosynthetic electron transport. PQ/ PQH2, plastoquinone/‐ol; PC, plastocyanin; Fd, ferredoxin.

Figure 2.

Pyridine nucleotides.

Figure 3.

Flavin cofactors.

Figure 4.

Tetrapyrrole compounds.

Figure 5.

Iron–sulfur clusters.

Figure 6.



Further Reading

Beinert H, Holm RH and Münck E (1997) Iron–sulfur clusters: Nature's modular, multipurpose structures. Science 277: 653–659.

Gray HB and Winkler JR (1996) Electron transfer in proteins. Annual Review of Biochemistry 65: 537–561.

Nugent JH (1996) Oxygenic photosynthesis. Electron transfer in photosystem I and photosystem II. European Journal of Biochemistry 237: 519–531.

Saraste M (1999) Oxidative phosphorylation at the fin des siècle. Science 283: 1488–1493.

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Roehm, Klaus‐Heinrich(Apr 2001) Electron Carriers: Proteins and Cofactors in Oxidative Phosphorylation. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1038/npg.els.0001373]