oxidative phosphorylation

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oxidative phosphorylation:

see phosphorylationphosphorylation,
chemical process in which a phosphate group is added to an organic molecule. In living cells phosphorylation is associated with respiration, which takes place in the cell's mitochondria, and photosynthesis, which takes place in the chloroplasts.
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The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Oxidative Phosphorylation

 

the synthesis in living cells of adenosine triphosphate (ATP) from adenosine diphosphate (ADP) and phosphoric acid at the expense of energy that derives from the oxidation of an organic substrate. As a result of oxidative phosphorylation, cells accumulate and subsequently utilize ATP—the most important high-energy compound known —to provide the energy for life processes. The principal substrates that are involved in oxidative phosphorylation are the organic acids that are formed in the tricarboxylic acid cycle.

Oxidative phosphorylation was first discovered in 1930 by the Soviet biochemist V. A. Engel’gardt. In 1939, V. A. Belitser and E. T. Tsybakova demonstrated that oxidative phosphorylation is associated with the transfer of electrons along the respiratory enzyme chain, which is located—as was later determined—in the inner mitochondrial membrane. Electrons enter the respiratory chain from reduced nicotinamide-adenine dinucleotide (NAD) or nicotinamide-adenine dinucleotide phosphate (NADP) and are successively transferred by coenzyme Q from compounds with a more negative oxidation-reduction potential to ones with a more positive potential.

The transfer of electrons along the chain terminates with the reduction of O2 by the complex enzyme cytochrome oxidase. Thus, substrate oxidation by oxygen is dependent on a series of oxidation-reduction reactions. After each reaction, the energy that accumulates in each molecule of oxidized substrate is released in small amounts, which ensures the maximum possible utilization of the energy; this maximum utilization occurs at energy conjugation points. The enzyme complex ATP-synthetase synthesizes ATP from ADP and phosphoric acid; it also controls the reverse process, the breakdown of ATP.

The ratio of P to O reflects the quantity of phosphate that is bonded during ADP phosphorylation relative to the amount of O2 that is absorbed. The transfer of two electrons through an energy conjugation point yields one molecule of ATP. The ratio of P to O is 3 for NAD oxidation and 2 for the oxidation of succinic acid.

S. A. OSTROUMOV

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

oxidative phosphorylation

[‚äk·sə‚dād·iv ‚fäs·fə·rə′lā·shən]
(biochemistry)
Conversion of inorganic phosphate to the energy-rich phosphate of adenosinetriphosphatase by reactions associated with the electron transfer system.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
This type of pseudo-respiration has the biochemical characteristics of normal respiration but does not involve ATP synthesis through oxidative phosphorylation (OxPhos).
DCs originates from the common dendritic progenitors (CDPs) in the bone marrow (BM) that use mitochondrial oxidative phosphorylation (OXPHOS) as a key metabolic energy source and have increased mitochondrial biogenesis.
Regional differences in OXPHOS enzyme expression might be present between the fundus, cardia, and antrum.
Most aggressive cancers show a glycolytic metabolic profile, and combination of glycolysis inhibitors with OxPhos inhibitors enhances the anticancer properties of this combination.
For patients with non-OXPHOS-related decreases in MEGS capacity in fresh muscle biopsies, the oxygen consumption rate would be an important tool to confirm the deficiency, since traditional OXPHOS enzyme assays are not discriminative.
However, on the other hand unlike nuclear DNA, mitochondrial DNA is not protected by histones and are physically associated with the inner mitochondrial membrane, where highly mutagenic oxygen radicals are generated as byproduct of OXPHOS in the respiratory chain (73) and leakage of these free radicals from the respiratory chain makes the mitochondria as a major intracellular source of ROS.
We have previously shown on clinical samples that both human breast cancer (HBC) and human colorectal cancer (HCC) are not purely glycolytic, but these tumors have sustained OXPHOS as a substantial provider of ATP [26-28].
Through their oxidation and breakdown, NADH and FADH2 help fuel OXPHOS, which is responsible for producing the energy that powers cells.
Resting naive T cells are metabolically quiescent and mainly rely on OXPHOS for energy production [13].
The mitochondrial genome contains 37 genes encoding 13 enzymes involved in OXPHOS, 22 types of transfer RNAs, and 2 types of ribosomal RNAs [35].
The results from muscle biopsies from 29 patients with deficiencies in PDHc and OXPHOS enzymes illustrate the rationale of our approach.
Since then, the shift from oxidative phosphorylation (OXPHOS) toward glycolysis and glutaminolysis has been considered as a metabolic reprogramming pathway of the inflammatory cells.