Oxidative phosphorylation or electron transport-linked phosphorylation or terminal oxidation is the metabolic pathway in which cells use enzymes to oxidize nutrients, thereby releasing chemical energy in order to produce adenosine triphosphate (ATP). In eukaryotes, this takes place inside mitochondria. Almost all aerobic organisms carry out oxidative phosphorylation. This pathway is so pervasive because it releases more energy than alternative fermentation processes such as anaerobic glycolysis.
An electron transport chain (ETC) is a series of protein complexes and other molecules that 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. Many of the enzymes in the electron transport chain are membrane-bound.
Coenzyme Q, also known as ubiquinone, is a coenzyme family that is ubiquitous in animals and most bacteria (hence the name ubiquinone). In humans, the most common form is coenzyme Q10 or ubiquinone-10. CoQ10 is not approved by the U.S. Food and Drug Administration (FDA) for the treatment of any medical condition; however, it is sold as a dietary supplement and is an ingredient in some cosmetics.
Pyridoxal phosphate (PLP, pyridoxal 5'-phosphate, P5P), the active form of vitamin B6, is a coenzyme in a variety of enzymatic reactions. The International Union of Biochemistry and Molecular Biology has catalogued more than 140 PLP-dependent activities, corresponding to ~4% of all classified activities. The versatility of PLP arises from its ability to covalently bind the substrate, and then to act as an electrophilic catalyst, thereby stabilizing different types of carbanionic reaction intermediates.
Succinate dehydrogenase (SDH) or succinate-coenzyme Q reductase (SQR) or respiratory complex II is an enzyme complex, found in many bacterial cells and in the inner mitochondrial membrane of eukaryotes. It is the only enzyme that participates in both the citric acid cycle and the electron transport chain. Histochemical analysis showing high succinate dehydrogenase in muscle demonstrates high mitochondrial content and high oxidative potential.
Mitochondrial 5-demethoxyubiquinone hydroxylase, also known as coenzyme Q7, hydroxylase, is an enzyme that in humans is encoded by the COQ7 gene. The clk-1 (clock-1) gene encodes this protein that is necessary for ubiquinone biosynthesis in the worm Caenorhabditis elegans and other eukaryotes. The mouse version of the gene is called mclk-1 and the human, fruit fly and yeast homolog COQ7.
4-Hydroxybenzoic acid, also known as p-hydroxybenzoic acid (PHBA), is a monohydroxybenzoic acid, a phenolic derivative of benzoic acid. It is a white crystalline solid that is slightly soluble in water and chloroform but more soluble in polar organic solvents such as alcohols and acetone. 4-Hydroxybenzoic acid is primarily known as the basis for the preparation of its esters, known as parabens, which are used as preservatives in cosmetics and some ophthalmic solutions. It is isomeric with 2-hydroxybenzoic acid, known as salicylic acid, a precursor to aspirin, and with 3-hydroxybenzoic acid.
The acetolactate synthase (ALS) enzyme is a protein found in plants and micro-organisms. ALS catalyzes the first step in the synthesis of the branched-chain amino acids.
The crotonase family comprises mechanistically diverse proteins that share a conserved trimeric quaternary structure, the core of which consists of 4 turns of a (beta/beta/alpha)n superhelix.
In enzymology, a 4-hydroxybenzoate polyprenyltransferase is an enzyme that catalyzes the chemical reaction
In enzymology, a chorismate lyase is an enzyme that catalyzes the chemical reaction
In enzymology, an oxalyl-CoA decarboxylase (OXC) (EC 4.1.1.8) is an enzyme primarily produced by the gastrointestinal bacterium Oxalobacter formigenes that catalyzes the chemical reaction
In enzymology, a [acyl-carrier-protein] S-malonyltransferase is an enzyme that catalyzes the chemical reaction
2-succinyl-6-hydroxy-2,4-cyclohexadiene-1-carboxylate synthase, also known as SHCHC synthase, is encoded by the menH gene in E.coli and functions in the synthesis of vitamin K. The specific step in the synthetic pathway that SHCHC synthase catalyzes is the conversion of 5-enolpyruvoyl-6-hydroxy-2-succinylcyclohex-3-ene-1-carboxylate to (1R,6R)-6-hydroxy-2-succinylcyclohexa-2,4-diene-1-carboxylate and pyruvate.
4-Hydroxy-3-methylbut-2-enyl diphosphate reductase (EC 1.17.1.2, isopentenyl-diphosphate:NADP+ oxidoreductase, LytB, (E)-4-hydroxy-3-methylbut-2-en-1-yl diphosphate reductase, HMBPP reductase, IspH, LytB/IspH) is an enzyme in the non-mevalonate pathway. It acts upon (E)-4-Hydroxy-3-methyl-but-2-enyl pyrophosphate (or "HMB-PP").
2-Methoxy-6-polyprenyl-1,4-benzoquinol methylase is an enzyme with systematic name S-adenosyl-L-methionine:2-methoxy-6-all-trans-polyprenyl-1,4-benzoquinol 5-C-methyltransferase. This enzyme catalyses the following chemical reaction
2-polyprenyl-6-hydroxyphenol methylase is an enzyme with systematic name S-adenosyl-L-methionine:3-(all-trans-polyprenyl)benzene-1,2-diol 2-O-methyltransferase. This enzyme catalyses the following chemical reaction
4-Hydroxy-tetrahydrodipicolinate synthase (EC 4.3.3.7, dihydrodipicolinate synthase, dihydropicolinate synthetase, dihydrodipicolinic acid synthase, L-aspartate-4-semialdehyde hydro-lyase (adding pyruvate and cyclizing), dapA (gene)) is an enzyme with the systematic name L-aspartate-4-semialdehyde hydro-lyase (adding pyruvate and cyclizing; (4S)-4-hydroxy-2,3,4,5-tetrahydro-(2S)-dipicolinate-forming). This enzyme catalyses the following chemical reaction
UbiX is a flavin prenyltransferase, catalysing the addition of dimethylallyl-monophosphate (DMAP) onto the N5 and C6 positions of FMN culminating in the formation of the prenylated FMN (prFMN) cofactor. The enzyme is involved in the ubiquinone biosynthesis pathway in E.coli from where it gets its name UbiX is associated with the UbiD enzymes as prFMN is utilised by UbiD enzymes in their function as reversible decarboxylases. Unusually for a prenyltransferase UbiX is not metal dependent.
Ferulic acid decarboxylases (Fdc) are decarboxylase enzymes capable of the reversible decarboxylation of aromatic carboxylic acids such as ferulic acid and cinnamic acid. Fdc's are fungal homologues of the E.coli UbiD enzyme which is involved in ubiquinone biosynthesis. This places Fdc within the wider UbiD enzyme family, representing a distinct clade within the family Presence of fdc1 and the associated pad1 genes were shown to be required for the decarboxylation of phenylacrylic acids in Saccharomyces cerevisiae.
