# Threonine racemase

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threonine racemase
Identifiers
EC number 5.1.1.6
CAS number 9024-11-7
Databases
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BRENDA BRENDA entry
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KEGG KEGG entry
MetaCyc metabolic pathway
PRIAM profile
PDB structures
Gene Ontology

In enzymology, a threonine racemase (EC 5.1.1.6) is an enzyme that catalyzes the chemical reaction

The Enzyme Commission number is a numerical classification scheme for enzymes, based on the chemical reactions they catalyze. As a system of enzyme nomenclature, every EC number is associated with a recommended name for the respective enzyme.

Catalysis is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst, which is not consumed in the catalyzed reaction and can continue to act repeatedly. Because of this, only very small amounts of catalyst are required to alter the reaction rate in principle.

A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the positions of electrons in the forming and breaking of chemical bonds between atoms, with no change to the nuclei, and can often be described by a chemical equation. Nuclear chemistry is a sub-discipline of chemistry that involves the chemical reactions of unstable and radioactive elements where both electronic and nuclear changes can occur.

L-threonine ${\displaystyle \rightleftharpoons }$ D-threonine

Hence, this enzyme has one substrate, L-threonine, and one product, D-threonine.

Products are the species formed from chemical reactions. During a chemical reaction reactants are transformed into products after passing through a high energy transition state. This process results in the consumption of the reactants. It can be a spontaneous reaction or mediated by catalysts which lower the energy of the transition state, and by solvents which provide the chemical environment necessary for the reaction to take place. When represented in chemical equations products are by convention drawn on the right-hand side, even in the case of reversible reactions. The properties of products such as their energies help determine several characteristics of a chemical reaction such as whether the reaction is exergonic or endergonic. Additionally the properties of a product can make it easier to extract and purify following a chemical reaction, especially if the product has a different state of matter than the reactants. Reactants are molecular materials used to create chemical reactions. The atoms aren't created or destroyed. The materials are reactive and reactants are rearranging during a chemical reaction. Here is an example of reactants: CH4 + O2. A non-example is CO2 + H2O or "energy".

This enzyme belongs to the family of isomerases, specifically those racemases and epimerases acting on amino acids and derivatives. The systematic name of this enzyme class is threonine racemase.

Isomerases are a general class of enzymes that convert a molecule from one isomer to another. Isomerases facilitate intramolecular rearrangements in which bonds are broken and formed. The general form of such a reaction is as follows:

Amino acids are organic compounds that contain amine (-NH2) and carboxyl (-COOH) functional groups, along with a side chain (R group) specific to each amino acid. The key elements of an amino acid are carbon (C), hydrogen (H), oxygen (O), and nitrogen (N), although other elements are found in the side chains of certain amino acids. About 500 naturally occurring amino acids are known (though only 20 appear in the genetic code) and can be classified in many ways. They can be classified according to the core structural functional groups' locations as alpha- (α-), beta- (β-), gamma- (γ-) or delta- (δ-) amino acids; other categories relate to polarity, pH level, and side chain group type (aliphatic, acyclic, aromatic, containing hydroxyl or sulfur, etc.). In the form of proteins, amino acid residues form the second-largest component (water is the largest) of human muscles and other tissues. Beyond their role as residues in proteins, amino acids participate in a number of processes such as neurotransmitter transport and biosynthesis.

## Related Research Articles

The enzyme phenylalanine racemase is the enzyme that acts on amino acids and derivatives. It activates both the L & D stereo isomers of phenylalanine to form L-phenylalanyl adenylate and D-phenylalanyl adenylate, which are bound to the enzyme. These bound compounds are then transferred to the thiol group of the enzyme followed by conversion of its configuration, the D-isomer being the more favorable configuration of the two, with a 7 to 3 ratio between the two isomers. The racemisation reaction of phenylalanine is coupled with the highly favorable hydrolysis of adenosine triphosphate (ATP) to adenosine monophosphate (AMP) and pyrophosphate (PP), thermodynamically allowing it to proceed. This reaction is then drawn forward by further hydrolyzing PP to inorganic phosphate (Pi), via Le Chatelier's principle.

The lactate racemase enzyme is involved in pyruvate metabolism. It is classified under the isomerase, racemase, epimerase, and enzyme acting on hydroxyl acids and derivatives classes of enzymes. It is found in certain halophilic archaea, such as Haloarcula marismortui and in a few species of bacteria, such as several Lactobacillus species, including Lactobacillus sakei, Lactobacillus curvatus, Lactobacillus plantarum, as well as in non-lactic acid bacteria such as Clostridium beijerinckii.

Methylmalonyl CoA epimerase is an enzyme involved in fatty acid catabolism that is encoded in human by the "MCEE" gene located on chromosome 2. It is routinely and incorrectly labeled as "methylmalonyl-CoA racemase". It is not a racemase because the CoA moiety has 5 other stereocenters.

Serine racemase is an enzyme which generates D-serine from L-serine. D-serine acts as a neuronal signaling molecule by activating NMDA receptors in the brain. In humans, the serine racemase protein is encoded by the SRR gene.

In enzymology, a 2-aminohexano-6-lactam racemase is an enzyme that catalyzes the chemical reaction

In enzymology, an alanine racemase is an enzyme that catalyzes the chemical reaction

In enzymology, an amino-acid racemase is an enzyme that catalyzes the chemical reaction

In enzymology, an arginine racemase is an enzyme that catalyzes the chemical reaction

In enzymology, an aspartate racemase is an enzyme that catalyzes the chemical reaction

In enzymology, a diaminopimelate epimerase is an enzyme that catalyzes the chemical reaction

In enzymology, glutamate racemase is an enzyme that catalyzes the chemical reaction

In enzymology, a lysine racemase is an enzyme that catalyzes the chemical reaction

In enzymology, a methionine racemase is an enzyme that catalyzes the chemical reaction

In enzymology, an ornithine racemase is an enzyme that catalyzes the chemical reaction

In enzymology, a proline racemase is an enzyme that catalyzes the chemical reaction

In enzymology, a protein-serine epimerase is an enzyme that catalyzes the chemical reaction

In enzymology, a threonine aldolase is an enzyme that catalyzes the chemical reaction

In enzymology, a threonine synthase (EC 4.2.3.1) is an enzyme that catalyzes the chemical reaction

D-threonine aldolase is an enzyme with systematic name D-threonine acetaldehyde-lyase (glycine-forming). This enzyme catalyses the following chemical reaction

D-Amino acids are amino acids where the stereogenic carbon alpha to the amino group has the D-configuration. For most naturally-occurring amino acids, this carbon has the L-configuration. D-Amino acids are most occasionally found in nature as residues in proteins. They are formed from ribosomally-derived D-amino acid residues.

## References

• Amos H (1954). "A racemase for threonine in Escherichia coli". J. Am. Chem. Soc. 76 (14): 3858. doi:10.1021/ja01643a083.

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