Nicotinamide adenine dinucleotide (NAD) is a coenzyme central to metabolism. Found in all living cells, NAD is called a dinucleotide because it consists of two nucleotides joined through their phosphate groups. One nucleotide contains an adenine nucleobase and the other, nicotinamide. NAD exists in two forms: an oxidized and reduced form, abbreviated as NAD+ and NADH (H for hydrogen), respectively.
In biochemistry, mixed acid fermentation is the metabolic process by which a six-carbon sugar is converted into a complex and variable mixture of acids. It is an anaerobic (non-oxygen-requiring) fermentation reaction that is common in bacteria. It is characteristic for members of the Enterobacteriaceae, a large family of Gram-negative bacteria that includes E. coli.
Catechol 2,3-dioxygenase (EC 1.13.11.2, 2,3-pyrocatechase, catechol 2,3-oxygenase, catechol oxygenase, metapyrocatechase, pyrocatechol 2,3-dioxygenase) is an enzyme with systematic name catechol:oxygen 2,3-oxidoreductase (decyclizing). This enzyme catalyses the following chemical reaction
Indoleamine-pyrrole 2,3-dioxygenase (IDO or INDO EC 1.13.11.52) is a heme-containing enzyme physiologically expressed in a number of tissues and cells, such as the small intestine, lungs, female genital tract or placenta. In humans is encoded by the IDO1 gene. IDO is involved in tryptophan metabolism. It is one of three enzymes that catalyze the first and rate-limiting step in the kynurenine pathway, the O2-dependent oxidation of L-tryptophan to N-formylkynurenine, the others being indolamine-2,3-dioxygenase 2 (IDO2) and tryptophan 2,3-dioxygenase (TDO). IDO is an important part of the immune system and plays a part in natural defense against various pathogens. It is produced by the cells in response to inflammation and has an immunosuppressive function because of its ability to limit T-cell function and engage mechanisms of immune tolerance. Emerging evidence suggests that IDO becomes activated during tumor development, helping malignant cells escape eradication by the immune system. Expression of IDO has been described in a number of types of cancer, such as acute myeloid leukemia, ovarian cancer or colorectal cancer. IDO is part of the malignant transformation process and plays a key role in suppressing the anti-tumor immune response in the body, so inhibiting it could increase the effect of chemotherapy as well as other immunotherapeutic protocols. Furthermore, there is data implicating a role for IDO1 in the modulation of vascular tone in conditions of inflammation via a novel pathway involving singlet oxygen.
6-Phosphogluconate dehydrogenase (6PGD) is an enzyme in the pentose phosphate pathway. It forms ribulose 5-phosphate from 6-phosphogluconate:
In enzymology, a 2-aminobenzenesulfonate 2,3-dioxygenase (EC 1.14.12.14) is an enzyme that catalyzes the chemical reaction
In enzymology, an anthranilate 1,2-dioxygenase (deaminating, decarboxylating) (EC 1.14.12.1) is an enzyme that catalyzes the chemical reaction
In enzymology, an anthranilate 3-monooxygenase (deaminating) (EC 1.14.13.35) is an enzyme that catalyzes the chemical reaction
In enzymology, a biphenyl 2,3-dioxygenase (EC 1.14.12.18) is an enzyme that catalyzes the chemical reaction
In enzymology, a toluene dioxygenase (EC 1.14.12.11) is an enzyme that catalyzes the chemical reaction
In enzymology, a quercetin 2,3-dioxygenase (EC 1.13.11.24) is an enzyme that catalyzes the chemical reaction
In enzymology, tryptophan 2,3-dioxygenase (EC 1.13.11.11) is a heme enzyme that catalyzes the oxidation of L-tryptophan (L-Trp) to N-formyl-L-kynurenine, as the first and rate-limiting step of the kynurenine pathway.
Dioxygenases are oxidoreductase enzymes. Aerobic life, from simple single-celled bacteria species to complex eukaryotic organisms, has evolved to depend on the oxidizing power of dioxygen in various metabolic pathways. From energetic adenosine triphosphate (ATP) generation to xenobiotic degradation, the use of dioxygen as a biological oxidant is widespread and varied in the exact mechanism of its use. Enzymes employ many different schemes to use dioxygen, and this largely depends on the substrate and reaction at hand.
2-Hydroxymuconate-6-semialdehyde dehydrogenase (EC 1.2.1.85, xylG [gene], praB [gene] ) is an enzyme with systematic name (2E,4Z)-2-hydroxy-6-oxohexa-2,4-dienoate:NAD+ oxidoreductase. This enzyme catalyses the following chemical reaction
9-cis-epoxycarotenoid dioxygenase (EC 1.13.11.51, nine-cis-epoxycarotenoid dioxygenase, NCED, AtNCED3, PvNCED1, VP14) is an enzyme in the biosynthesis of abscisic acid (ABA), with systematic name 9-cis-epoxycarotenoid 11,12-dioxygenase. This enzyme catalyses the following chemical reaction
Hypoxia-inducible factor-proline dioxygenase (EC 1.14.11.29, HIF hydroxylase) is an enzyme with systematic name hypoxia-inducible factor-L-proline, 2-oxoglutarate:oxygen oxidoreductase (4-hydroxylating). This enzyme catalyses the following chemical reaction
Benzoyl-CoA 2,3-dioxygenase (EC 1.14.12.21, benzoyl-CoA dioxygenase/reductase, BoxBA, BoxA/BoxB system) is an enzyme with systematic name benzoyl-CoA,NADPH:oxygen oxidoreductase (2,3-hydroxylating). This enzyme catalyses the following chemical reaction
6-hydroxy-3-succinoylpyridine 3-monooxygenase (EC 1.14.13.163, 6-hydroxy-3-succinoylpyridine hydroxylase, hspA (gene), hspB (gene)) is an enzyme with systematic name 4-(6-hydroxypyridin-3-yl)-4-oxobutanoate,NADH:oxygen oxidoreductase (3-hydroxylating, succinate semialdehyde releasing). This enzyme catalyses the following chemical reaction
Lycopene β-cyclase is an enzyme with systematic name carotenoid beta-end group lyase (decyclizing). This enzyme catalyses the following chemical reaction
Alpha-ketoglutarate-dependent hydroxylases are a major class of non-heme iron proteins that catalyse a wide range of reactions. These reactions include hydroxylation reactions, demethylations, ring expansions, ring closures, and desaturations. Functionally, the αKG-dependent hydroxylases are comparable to cytochrome P450 enzymes. Both use O2 and reducing equivalents as cosubstrates and both generate water.
