The citric acid cycle —also known as the Krebs cycle, Szent-Györgyi-Krebs cycle or the TCA cycle (tricarboxylic acid cycle)—is a series of chemical reactions to release stored energy through the oxidation of acetyl-CoA derived from carbohydrates, fats, and proteins. The Krebs cycle is used by organisms that respire (as opposed to organisms that ferment) to generate energy, either by anaerobic respiration or aerobic respiration. In addition, the cycle provides precursors of certain amino acids, as well as the reducing agent NADH, that are used in numerous other reactions. Its central importance to many biochemical pathways suggests that it was one of the earliest components of metabolism. Even though it is branded as a 'cycle', it is not necessary for metabolites to follow only one specific route; at least three alternative segments of the citric acid cycle have been recognized.
Eicosanoids are signaling molecules made by the enzymatic or non-enzymatic oxidation of arachidonic acid or other polyunsaturated fatty acids (PUFAs) that are, similar to arachidonic acid, around 20 carbon units in length. Eicosanoids are a sub-category of oxylipins, i.e. oxidized fatty acids of diverse carbon units in length, and are distinguished from other oxylipins by their overwhelming importance as cell signaling molecules. Eicosanoids function in diverse physiological systems and pathological processes such as: mounting or inhibiting inflammation, allergy, fever and other immune responses; regulating the abortion of pregnancy and normal childbirth; contributing to the perception of pain; regulating cell growth; controlling blood pressure; and modulating the regional flow of blood to tissues. In performing these roles, eicosanoids most often act as autocrine signaling agents to impact their cells of origin or as paracrine signaling agents to impact cells in the proximity of their cells of origin. Eicosanoids may also act as endocrine agents to control the function of distant cells.
Cytochromes P450 are a superfamily of enzymes containing heme as a cofactor that mostly, but not exclusively, function as monooxygenases. In mammals, these proteins oxidize steroids, fatty acids, and xenobiotics, and are important for the clearance of various compounds, as well as for hormone synthesis and breakdown. In 1963, Estabrook, Cooper, and Rosenthal described the role of CYP as a catalyst in steroid hormone synthesis and drug metabolism. In plants, these proteins are important for the biosynthesis of defensive compounds, fatty acids, and hormones.
Ferredoxins 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.
In the mitochondrion, the matrix is the space within the inner membrane. The word "matrix" stems from the fact that this space is viscous, compared to the relatively aqueous cytoplasm. The mitochondrial matrix contains the mitochondrial DNA, ribosomes, soluble enzymes, small organic molecules, nucleotide cofactors, and inorganic ions.[1] The enzymes in the matrix facilitate reactions responsible for the production of ATP, such as the citric acid cycle, oxidative phosphorylation, oxidation of pyruvate, and the beta oxidation of fatty acids.
Shikimic acid, more commonly known as its anionic form shikimate, is a cyclohexene, a cyclitol and a cyclohexanecarboxylic acid. It is an important biochemical metabolite in plants and microorganisms. Its name comes from the Japanese flower shikimi, from which it was first isolated in 1885 by Johan Fredrik Eykman. The elucidation of its structure was made nearly 50 years later.
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.
Any enzyme system that includes cytochrome P450 protein or domain can be called a P450-containing system.
In enzymology, a 2-oxoglutarate synthase (EC 1.2.7.3) is an enzyme that catalyzes the chemical reaction
In enzymology, a 3-methyl-2-oxobutanoate dehydrogenase (ferredoxin) (EC 1.2.7.7) is an enzyme that catalyzes the chemical reaction
In enzymology, an indolepyruvate ferredoxin oxidoreductase (EC 1.2.7.8) is an enzyme that catalyzes the chemical reaction
In enzymology, a pyruvate synthase is an enzyme that catalyzes the interconversion of pyruvate and acetyl-CoA. It is also called pyruvate:ferredoxin oxidoreductase (PFOR).
In enzymology, a linoleate diol synthase (EC 1.13.11.44) is an enzyme that catalyzes the chemical reaction
In enzymology, a glutamate synthase (ferredoxin) (EC 1.4.7.1) is an enzyme that catalyzes the chemical reaction
Damascenones are a series of closely related chemical compounds that are components of a variety of essential oils. The damascenones belong to a family of chemicals known as rose ketones, which also includes damascones and ionones. beta-Damascenone is a major contributor to the aroma of roses, despite its very low concentration, and is an important fragrance chemical used in perfumery.
Pentalenolactone synthase is an enzyme with systematic name pentalenolactone-F:oxidized-ferredoxin oxidoreductase . This enzyme catalyse the following chemical reaction
1-deoxypentalenic acid 11beta-hydroxylase (EC 1.14.11.35, PTLH (gene), SAV2991 (gene), PNTH (gene)) is an enzyme with systematic name 1-deoxypentalenic acid,2-oxoglutarate:oxygen oxidoreductase. This enzyme catalyses the following chemical reaction
Tetrahydrocannabinolic acid (THCA) synthase is an enzyme responsible for catalyzing the formation of THCA from cannabigerolic acid (CBGA). THCA is the direct precursor of tetrahydrocannabinol (THC), the principal psychoactive component of cannabis, which is produced from various strains of Cannabis sativa. Therefore, THCA synthase is considered to be a key enzyme controlling cannabis psychoactivity. Polymorphisms of THCA synthase result in varying levels of THC in Cannabis plants, resulting in "drug-type" and "fiber-type" C. sativa varieties.
Cannabidiolic acid synthase is an enzyme with systematic name cannabigerolate:oxygen oxidoreductase . It is an oxidoreductase found in Cannabis sativa that catalyses the formation of cannabidiolate, a carboxylated precursor of cannabidiol.
Chlorophyllide a and Chlorophyllide b are the biosynthetic precursors of chlorophyll a and chlorophyll b respectively. Their propionic acid groups are converted to phytyl esters by the enzyme chlorophyll synthase in the final step of the pathway. Thus the main interest in these chemical compounds has been in the study of chlorophyll biosynthesis in plants, algae and cyanobacteria. Chlorophyllide a is also an intermediate in the biosynthesis of bacteriochlorophylls.
