dehydrogenase

Enzymes catalyzing oxidation-reduction of substances

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Dehydrogenase refers to a class of catalytic substances (such as sugars Organic acid 、 amino acid ）Proceed Redox reaction Enzyme of, in enzymology Belongs to in the category Oxidoreductases 。 The substrate oxidized in the reaction is called Hydrogen donor or Electron donor The reduced substrate is called hydrogen receptor or electron acceptor 。 When the receptor is oxygen, the enzyme that catalyzes the reaction is called oxidase In other cases, it is called dehydrogenase. Different dehydrogenases are almost named after their substrates. Most redox reactions in organisms are catalyzed by dehydrogenase and oxidase. Substance via dehydrogenase catalytic oxidation , finally passed Electron transfer chain When oxidized by oxygen Oxidative phosphorylation generate Adenosine triphosphate （ ATP ）It is the main way for heterotrophic organisms to obtain energy. Soil dehydrogenase activity is easy Be present Extracellular in soil Phenol oxidase , or can catalyze dehydrogenase reaction inorganic compound Covered up. Copper can be carried out with the final product of reaction Abiotic The result of dehydrogenase activity in polluted soil is low. Although dehydrogenase is susceptible to soil environment But it is not suitable as an indicator because it cannot be accumulated in the soil in a complex form soil quality Indicators of change, and soil respiration , Microorganism Biomass Nonsignificant relevance 。^[1]

Chinese name: dehydrogenase
Foreign name: dehydrogenases

Definition: A class of enzymes that catalyze the redox reaction of substances
Features: Accelerate reaction rate

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What is dehydrogenase

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stay enzymology It belongs to the first category in the classification. The oxidized substrate in the reaction is called Hydrogen donor or Electron donor The reduced substrate is called hydrogen receptor or electron acceptor 。 When the receptor is O2 The enzyme that catalyzes the reaction is called oxidase In other cases, it is called dehydrogenase. Different dehydrogenases are almost named after their substrates. as Succinate dehydrogenase Catalytic reaction.

The reaction is reversible. Under certain conditions, the equilibrium of the reaction tends to the left, so the enzyme can be called Fumaric acid reductase 。 Sometimes the product can also be named for its special importance, such as Cortisone Reductase, etc.

type

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Dehydrogenases are the most diverse of known enzymes, among which dehydrogenation of alcohol group (- CHOH), aldehyde, ketone group (- HCO or - RCO) and alkyl gene (- CH2-CH2 -) in the catalytic donor is the most common. Natural receptors mainly include Nicotinamide adenine dinucleotide (NAD+) and Nicotinamide adenine dinucleotide phosphate （ NADP+ ）And Cytochrome 。

Reaction principle

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Figure 2

The natural receptors for most dehydrogenases are NAD +Or NADP+ [denoted by NAD (P)+below], for example Malate dehydrogenase ， Isocitrate dehydrogenase Etc. The substrate of dehydrogenase is catalysed by such dehydrogenase to reduce NAD (P)+to NAD (P) H. Other dehydrogenase Flavin by Cofactor , auxiliary base in catalytic reaction In Redox 。 for example Succinate dehydrogenase , prototype reduction nicotinamide Adenine Ridge II nucleotide （ NADH ）Dehydrogenase, choline Dehydrogenase, etc. NADH and some dehydrogenase substrates that directly use flavin as a cofactor are catalyzed by dehydrogenase and finally passed through Cytochrome The system is oxidized by oxygen, and the energy released at this time is needed by the body. They are associated with the cytochrome system Electron transfer chain The connection of can be generally represented by a simple diagram (Figure 2).

α- Glycerophosphate , choline, etc. can be connected with the electron transfer chain at the position equivalent to succinate dehydrogenase through the corresponding dehydrogenase.

NADH Dehydrogenase Succinate dehydrogenase Both contain lutein cofactor. The cofactor of NADH dehydrogenase is Flavin mononucleotide (FMN), with no covalent bond And Enzyme protein combination. The cofactor of succinate dehydrogenase is Flavin adenine dinucleotide (FAD), with covalent bond histidine combination.

NADH dehydrogenase and succinate dehydrogenase both contain Non heme iron And acid unstable sulfur. utilize Paramagnetic resonance Understand the role of iron and sulfur in the process of electron transfer Redox And their role in the process of enzyme and membrane binding, Iron sulfur center Unstable, often Enzyme inactivation The iron sulfur center is also enzyme inhibitor Of Action site 。

Most organisms Redox reaction Both in dehydrogenase and oxidase Under the catalysis of. Substance via dehydrogenase catalytic oxidation , finally passed Electron transfer chain When oxidized by oxygen Oxidative phosphorylation generate Adenosine triphosphate （ ATP ）It is the main way for heterotrophic organisms to obtain energy.

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