| Complex Name | Abbreviation | Metabolic Pathway | Overall Reaction Catalyzed | E1 / E2 subunits (or analogous components) |
|---|---|---|---|---|
| Pyruvate dehydrogenase complex | PDHc | Carbohydrate metabolism; links glycolysis to the TCA cycle | Pyruvate + CoA + NAD+ → Acetyl-CoA + CO2 + NADH. DLD/E3 catalyzes the shared terminal step: oxidation of E2-bound dihydrolipoamide to lipoamide with reduction of NAD+ to NADH. | E1: pyruvate dehydrogenase (PDHA1/PDHB heterotetramer); E2: dihydrolipoamide S-acetyltransferase (DLAT). In human PDHc, E3 is tethered via E3-binding protein (PDHX/E3BP). (pqac-00000009, pqac-00000012, pqac-00000048, pqac-00000050) |
| α-Ketoglutarate dehydrogenase complex | KGDHc | Tricarboxylic acid cycle | 2-Oxoglutarate + CoA + NAD+ → Succinyl-CoA + CO2 + NADH. DLD/E3 reoxidizes the lipoyl cofactor on E2 and transfers electrons to NAD+. | E1: 2-oxoglutarate dehydrogenase (OGDH/OGDHL family context); E2: dihydrolipoyl succinyltransferase (DLST). (pqac-00000009, pqac-00000010, pqac-00000007) |
| Branched-chain α-keto acid dehydrogenase complex | BCKDHc | Branched-chain amino acid catabolism (leucine, isoleucine, valine) | Branched-chain α-keto acids + CoA + NAD+ → branched-chain acyl-CoAs + CO2 + NADH. DLD/E3 performs the common final reoxidation of dihydrolipoamide and reduction of NAD+ to NADH. | E1: branched-chain α-keto acid dehydrogenase E1 (BCKDHA/BCKDHB); E2: dihydrolipoamide branched-chain transacylase E2 (DBT). (pqac-00000009, pqac-00000010, pqac-00000011) |
| α-Ketoadipate dehydrogenase complex | KADHc | Lysine, hydroxylysine, and tryptophan catabolism | 2-Oxoadipate + CoA + NAD+ → glutaryl-CoA + CO2 + NADH. DLD/E3 again carries out the terminal lipoyl reoxidation/NADH-producing step. | E1: 2-oxoadipate dehydrogenase (DHTKD1); E2: shares the E2 component DLST with KGDHc in mammalian mitochondria. (pqac-00000009, pqac-00000010) |
| Glycine cleavage system | GCS | Glycine degradation and mitochondrial one-carbon metabolism | Glycine + tetrahydrofolate + NAD+ → 5,10-methylene-THF + CO2 + NH3 + NADH. DLD functions as the L-protein, reoxidizing the reduced lipoyl moiety on H-protein while reducing NAD+ to NADH. | Analogous components rather than E1/E2: P-protein = glycine decarboxylase (GLDC), H-protein = GCSH, T-protein = aminomethyltransferase (AMT), L-protein = DLD. (pqac-00000011, pqac-00000038, pqac-00000039) |


*Table: This table summarizes the mitochondrial enzyme systems that use human DLD as their shared E3/L-protein component. It highlights the pathway context, overall chemistry, and partner catalytic subunits/components needed to interpret DLD’s functional annotation.*