Pyruvate oxidase

Related Reading

In enzymology, pyruvate oxidase is an enzyme that catalyzes chemical reactions. The enzyme's three substrates are pyruvate, phosphate and O₂, and its three products are acetyl phosphate, CO₂ and H₂O₂. This enzyme belongs to the family of oxidoreductases, especially those that use oxygen as an acceptor to act on the aldehyde or oxo group of the donor. The systematic name of this enzyme class is pyruvate: 2-oxygen oxidoreductase (phosphorylation). Other commonly used names include pyruvate oxidase and phosphate-dependent pyruvate oxidase. This enzyme is involved in the metabolism of pyruvate. It has 2 cofactors: FAD and thiamine diphosphate.

Introductions

Pyruvate oxidase has been isolated from Escherichia coli in crystalline form and at a high state of purity. Pyruvate oxidase binds both flavin-adenine dinucleotide and thiamine pyrophosphate as prosthetic groups. Molecular weight measurements indicate that the crystalline oxidase exists in solution as a tetramer. The minimal molecular weight of the oxidase, based on flavin-adenine dinucleotide content, is 66,000, whereas the molecular weight of the oxidase, as measured by equilibrium sedimentation, is approximately 265,000. This paper reports the spectral properties, the amino acid content, the kinetic constants, and some of the enzymic activities of crystalline oxidase.

Research

A new type of pyruvate oxidase has been discovered in Proteus hemolyticus, which can catalyze the acetylation of CoA in the presence of pyruvate, oxygen and FAD. The enzyme was partially purified by centrifugation, ammonium sulfate precipitation and hydroxyapatite chromatography. It was found that the enzyme activity has two parts. The ratio of oxygen consumed by purified enzyme to acetyl-CoA produced is 1. In the presence of excess catalase, the rate of oxygen absorption is one-half. Therefore, the assumed reaction is: pyruvic acid + CoA + 02 = acetyl CoA + CO2 + H2O2. For this new enzyme, the researchers proposed the abbreviation of pyruvate oxidase (CoA acetylation).

Applications

Pyruvate oxidase has been used as a tool enzyme for microplate readers, semi-automatic analyzers, dual-reagent automatic analyzers, and manual methods. Pyruvate oxidase reacts endogenous pyruvate in the sample to generate hydrogen peroxide, and hydrogen peroxide generates water and oxygen under the action of catalase to consume endogenous pyruvate in the sample. After arsenic enters the body, this protoplasmic poison has a great affinity for the sulfhydryl group of the protein. Especially combined with the sulfhydryl group of pyruvate oxidase, it becomes a complex of pyruvate oxidase and arsenic, which makes the enzyme inactive, affects the normal metabolism of cells, and causes cell death. When inosine is involved, it participates in nucleic acid metabolism, energy metabolism and protein synthesis in the body. Inosine can directly enter the body cell through the cell membrane, activate pyruvate oxidase, and increase the activity of coenzyme A, thereby making it in a low-energy hypoxic state The underlying cells can continue to metabolize smoothly, help restore liver cell function, stimulate the production of antibodies in the body and promote the absorption of iron in the intestine. And participate in human energy metabolism and protein synthesis. The mitochondrial inner space surrounded by the inner membrane and cristae of the mitochondrial matrix contains many proteins and lipids. The enzymes that catalyze the oxidation of fatty acids and pyruvate in the tricarboxylic acid cycle are also present in the matrix, which is beneficial to tricarboxylic acids.