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In chemistry, charge-transfer (CT) complex, or electron donor-acceptor complex, describes a type of supramolecular assembly of two or more molecules or ions. The assembly consists of two molecules that self-attract through electrostatic forces, i.e., one has at least partial negative charge and the partner has partial positive charge, referred ...
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.
The organic or inorganic substances (e.g., oxygen) used as electron acceptors needed in the catabolic processes of aerobic or anaerobic respiration and fermentation are not taken into account here. For example, plants are lithotrophs because they use water as their electron donor for the electron transport chain across the thylakoid membrane.
Proper names of oxidoreductases are formed as "donor:acceptor oxidoreductase"; however, other names are much more common. [ citation needed ] The common name is " donor dehydrogenase " when possible, such as glyceraldehyde-3-phosphate dehydrogenase for the second reaction above.
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.
A phylloquinone, sometimes called vitamin K 1, [16] is the next early electron acceptor in PSI. It oxidizes A 1 in order to receive the electron and in turn is re-oxidized by F x, from which the electron is passed to F b and F a. [16] [17] The reduction of F x appears to be the rate-limiting step. [15]
Charge-transfer interactions are also important in protein stabilization and surface interaction. In general donor-acceptor processes, one can think of excess electron density being present which can be donated to an electrophilic species. In aqueous media, these solute interactions are primarily due to pi orbital electron effects. [11]
The electron donating power of a donor molecule is measured by its ionization potential, which is the energy required to remove an electron from the highest occupied molecular orbital . The overall energy balance (ΔE), i.e., energy gained or lost, in an electron donor-acceptor transfer is determined by the difference between the acceptor's ...