Branched-chain alpha-keto acid dehydrogenase complex (BCKDH) (BCKDH)

The branched-chain alpha-keto acid dehydrogenase (BCKDH) complex is a mitochondrial multienzyme assembly that plays a critical role in the oxidative catabolism of the branched-chain amino acids (BCAAs) leucine, isoleucine, and valine (UniProt: P12694). It catalyzes the rate-limiting step of this pathway, converting branched-chain alpha-keto acids (BCKAs) into their corresponding acyl-CoA esters (StatPearls: Maple Syrup Urine Disease). Genetic mutations in the components of this complex, such as the E1 alpha, E1 beta, or E2 subunits, result in Maple Syrup Urine Disease (MSUD), a condition marked by the toxic accumulation of BCAAs and BCKAs that leads to severe neurotoxicity (NIH: Genetics Home Reference). Beyond rare genetic disorders, suppressed BCKDH activity is increasingly linked to common metabolic conditions like obesity and type 2 diabetes, where elevated BCAA levels serve as biomarkers for insulin resistance (Nature Communications, 2014). Therapeutic strategies often focus on increasing the activity of the complex, either through thiamine supplementation for responsive genetic variants or by using small molecules like sodium phenylbutyrate and BT2 to inhibit the regulatory kinase BCKDK, which normally keeps the complex in an inactive, phosphorylated state (PubMed: 21316315).

Other names

BCKDCBranched-chain keto acid dehydrogenase2-oxoisovalerate dehydrogenase complexBCKDH complexBranched-chain alpha-ketoacid dehydrogenase

Activation of the enzyme complex through inhibition of the regulatory branched-chain alpha-keto acid dehydrogenase kinase (BCKDK) or through cofactor supplementation with thiamine pyrophosphate.