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An electron transport chain (ETC [1]) is a series of protein complexes and other molecules which transfer electrons from electron donors to electron acceptors via redox reactions (both reduction and oxidation occurring simultaneously) and couples this electron transfer with the transfer of protons (H + ions) across a membrane.
A protein called divalent metal transporter 1 , which can transport several divalent metals across the plasma membrane, then transports iron across the enterocyte's cell membrane into the cell. If the iron is bound to heme, it is instead transported across the apical membrane by heme carrier protein 1 (HCP1). [ 11 ]
Oxidative phosphorylation contributes the majority of the ATP produced, compared to glycolysis and the Krebs cycle. While the ATP count is glycolysis and the Krebs cycle is two ATP molecules, the electron transport chain contributes, at most, twenty-eight ATP molecules. A contributing factor is due to the energy potentials of NADH and FADH 2.
The high reduction potential of the N2 cluster and the relative proximity of the other clusters in the chain enable efficient electron transfer over long distance in the protein (with transfer rates from NADH to N2 iron-sulfur cluster of about 100 μs). [12] [13] The equilibrium dynamics of Complex I are primarily driven by the quinone redox cycle.
Furthermore, theories have been put forward to take into account the effects of vibronic coupling on electron transfer, in particular, the PKS theory of electron transfer. [10] In proteins, ET rates are governed by the bond structures: the electrons, in effect, tunnel through the bonds comprising the chain structure of the proteins.
Ferredoxins (from Latin ferrum: iron + redox, often abbreviated "fd") are iron–sulfur proteins that mediate electron transfer in a range of metabolic reactions. The term "ferredoxin" was coined by D.C. Wharton of the DuPont Co. and applied to the "iron protein" first purified in 1962 by Mortenson, Valentine, and Carnahan from the anaerobic bacterium Clostridium pasteurianum.
The [Fe 4 S 4] electron-transfer proteins ([Fe 4 S 4] ferredoxins) may be further subdivided into low-potential (bacterial-type) and high-potential (HiPIP) ferredoxins. Low- and high-potential ferredoxins are related by the following redox scheme: 4Fe-4S clusters serve as electron-relays in proteins.
Protein anabolism is the process by which proteins are formed from amino acids. It relies on five processes: amino acid synthesis, transcription , translation , post translational modifications , and protein folding .