Center for Bioinformatics
Oxidoreductases | Transferases | Hydrolases | Lyases | Isomerases | Ligases

Basic Information

Enzyme Number

Official Name

dihydrolipoyl dehydrogenase

Name from literature

branched-chain alpha-keto acid dehydrogenase complex

Pathway from literature

the branched-chain amino acid catabolism

Pathway from KEGG

Amino Acid Metabolism; Glycine, serine and threonine metabolism; map00260

Amino Acid Metabolism; Valine, leucine and isoleucine degradation; map00280

Carbohydrate Metabolism; Pyruvate metabolism; map00620

Carbohydrate Metabolism; Glycolysis / Gluconeogenesis; map00010

Carbohydrate Metabolism; Citrate cycle (TCA cycle); map00020

Amino Acid Metabolism; Alanine and aspartate metabolism; map00252


Rat (10116)

Genome localization

6q16[298942 ],


A flavoprotein (FAD). A component of the multienzyme 2-oxo-acid dehydrogenase complexes. In the pyruvate dehydrogenase complex, it binds to the core of EC, dihydrolipoyllysine-residue acetyltransferase, and catalyses oxidation of its dihydrolipoyl groups. It plays a similar role in the oxoglutarate and 3-methyl-2-oxobutanoate dehydrogenase complexes. Another substrate is the dihydrolipoyl group in the H-protein of the glycine-cleavage system (click here for diagram), in which it acts, together with EC, glycine dehydrogenase (decarboxylating), and EC, aminomethyltransferase, to break down glycine. It can also use free dihydrolipoate, dihydrolipoamide or dihydrolipoyllysine as substrate. This enzyme was first shown to catalyse the oxidation of NADH by methylene blue; this activity was called diaphorase. The glycine cleavage system is composed of four components that only loosely associate: the P protein (EC, the T protein (EC, the L protein (EC and the lipoyl-bearing H protein [6].

Rate-limiting Description

"The mechanism responsible for this phenomenon is attributed to activation of the branched-chain alpha-keto acid dehydrogenase (BCKDH) complex, which catalyzes the second-step reaction of the BCAA catabolic pathway and is the rate-limiting enzyme in the pathway." (15173434)

"Clofibric acid (an active metabolite of clofibrate) is known to promote the BCAA catabolism by activation of branched-chain alpha-keto acid dehydrogenase complex (BCKDC), the rate-limiting enzyme of the BCAA catabolism." (16616211)

"The rate-limiting step of branched-chain amino acid oxidation is performed by the mitochondrial enzyme branched-chain alpha-keto acid dehydrogenase (BCKAD), which is regulated by a deactivating kinase." (11641455)

"Feeding the BCAA diet increased serum BCAA concentrations and activity of the hepatic branched-chain alpha-keto acid dehydrogenase complex, the rate-limiting enzyme in the catabolism of BCAA, suggesting that dietary BCAA promotes BCAA catabolism." (10885793)

Gene ontology

Gene ontology

GO:0050660 (F) FAD binding [Q6P6R2 ];
GO:0009055 (F) electron carrier activity [Q6P6R2 ];
GO:0005759 (C) mitochondrial matrix [Q6P6R2 ];
GO:0055114 (P) oxidation reduction [Q6P6R2 ];
GO:0045454 (P) cell redox homeostasis [Q6P6R2 ];
GO:0004148 (F) dihydrolipoyl dehydrogenase activity [Q6P6R2 ];

Subcellular localization


mitochondrion [Q6P6R2 ];




Entrez Gene


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  Last Modified: 2009-03-24  
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