The citric acid cycle—also known as the Krebs cycle, Szent–Györgyi–Krebs cycle, or TCA cycle —is a series of biochemical reactions to release the energy stored in nutrients through the oxidation of acetyl-CoA derived from carbohydrates, fats, proteins, and alcohol. The chemical energy released is available in the form of ATP. The Krebs cycle is used by organisms that respire 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.
Carbonic acid is a chemical compound with the chemical formula H2CO3. The molecule rapidly converts to water and carbon dioxide in the presence of water. However, in the absence of water, it is quite stable at room temperature. The interconversion of carbon dioxide and carbonic acid is related to the breathing cycle of animals and the acidification of natural waters.
A triglyceride is an ester derived from glycerol and three fatty acids. Triglycerides are the main constituents of body fat in humans and other vertebrates as well as vegetable fat. They are also present in the blood to enable the bidirectional transference of adipose fat and blood glucose from the liver and are a major component of human skin oils.
Malic acid is an organic compound with the molecular formula HO2CCH(OH)CH2CO2H. It is a dicarboxylic acid that is made by all living organisms, contributes to the sour taste of fruits, and is used as a food additive. Malic acid has two stereoisomeric forms, though only the L-isomer exists naturally. The salts and esters of malic acid are known as malates. The malate anion is a metabolic intermediate in the citric acid cycle.
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.
Polyhydroxyalkanoates or PHAs are polyesters produced in nature by numerous microorganisms, including through bacterial fermentation of sugars or lipids. When produced by bacteria they serve as both a source of energy and as a carbon store. More than 150 different monomers can be combined within this family to give materials with extremely different properties. These plastics are biodegradable and are used in the production of bioplastics.
Anaplerotic reactions, a term coined by Hans Kornberg and originating from the Greek ἀνά= 'up' and πληρόω= 'to fill', are chemical reactions that form intermediates of a metabolic pathway. Examples of such are found in the citric acid cycle. In normal function of this cycle for respiration, concentrations of TCA intermediates remain constant; however, many biosynthetic reactions also use these molecules as a substrate. Anaplerosis is the act of replenishing TCA cycle intermediates that have been extracted for biosynthesis.
Pyruvate carboxylase (PC) encoded by the gene PC is an enzyme of the ligase class that catalyzes the physiologically irreversible carboxylation of pyruvate to form oxaloacetate (OAA).
In biochemistry and metabolism, beta oxidation (also β-oxidation) is the catabolic process by which fatty acid molecules are broken down in the cytosol in prokaryotes and in the mitochondria in eukaryotes to generate acetyl-CoA. Acetyl-CoA enters the citric acid cycle, generating NADH and FADH2, which are electron carriers used in the electron transport chain. It is named as such because the beta carbon of the fatty acid chain undergoes oxidation and is converted to a carbonyl group to start the cycle all over again. Beta-oxidation is primarily facilitated by the mitochondrial trifunctional protein, an enzyme complex associated with the inner mitochondrial membrane, although very long chain fatty acids are oxidized in peroxisomes.
Enanthic acid, also called heptanoic acid, is an organic compound composed of a seven-carbon chain terminating in a carboxylic acid functional group. It is a colorless oily liquid with an unpleasant, rancid odor. It contributes to the odor of some rancid oils. It is slightly soluble in water, but very soluble in ethanol and ether. Salts and esters of enanthic acid are called enanthates or heptanoates.
Pyruvate carboxylase deficiency is an inherited disorder that causes lactic acid to accumulate in the blood. High levels of these substances can damage the body's organs and tissues, particularly in the nervous system. Pyruvate carboxylase deficiency is a rare condition, with an estimated incidence of 1 in 250,000 births worldwide. Type A of the disease appears to be much more common in some Algonkian Indian tribes in eastern Canada, while the type B disease is more present in European populations.
Methylmalonic acid (MMA) is a chemical compound from the group of dicarboxylic acids. It consists of the basic structure of malonic acid and also carries a methyl group. The salts of methylmalonic acid are called methylmalonates.
Short-chain fatty acids (SCFAs) are fatty acids of two to six carbon atoms. The SCFAs' lower limit is interpreted differently, either with one, two, three or four carbon atoms. Derived from intestinal microbial fermentation of indigestible foods, SCFAs in human gut are acetic, propionic and butyric acid. They are the main energy source of colonocytes, making them crucial to gastrointestinal health. SCFAs all possess varying degrees of water solubility, which distinguishes them from longer chain fatty acids that are immiscible.
In enzymology, a homoserine dehydrogenase (EC 1.1.1.3) is an enzyme that catalyzes the chemical reaction
A beta hydroxy carboxylic acid or β-hydroxy carboxylic acid (BHA) is a carboxylic acid containing a hydroxy functional group separated by two carbon atoms. They are related to alpha hydroxy acids, in which the two functional groups are separated by only one carbon atom.
Triheptanoin, sold under the brand name Dojolvi, is a medication for the treatment of children and adults with molecularly confirmed long-chain fatty acid oxidation disorders (LC-FAOD).
The γ-hydroxybutyrate (GHB) receptor (GHBR), originally identified as GPR172A, is an excitatory G protein-coupled receptor (GPCR) that binds the neurotransmitter and psychoactive drug γ-hydroxybutyric acid (GHB). As solute carrier family 52 member 2 (SLC52A2), it is also a transporter for riboflavin.
3-Oxopentanoic acid, or beta-ketopentanoate, is a 5-carbon ketone body. It is made from odd carbon fatty acids in the liver and rapidly enters the brain.
γ-Hydroxyvaleric acid (GHV), also known as 4-methyl-GHB, is a designer drug related to γ-hydroxybutyric acid (GHB). It is sometimes seen on the grey market as a legal alternative to GHB, but with lower potency and higher toxicity, properties which have tended to limit its recreational use.
Hydroxyvaleric acid or hydroxypentanoic acid may refer to the following compounds:
