alpha-ketoglutarate dehydrogenase complex
– acts similarly to PDH complex- oxidative decarboxylation of alpha-ketoglutarate to form succinyl-CoA- generates second CO2 of citric acid cycle-generates second NADH of citric acid cycle- inhibited by ATP, NADH, and succinyl-CoA- activated by ADP and Ca2+
The alpha-ketoglutarate dehydrogenase complex (KGDH complex) is an important enzyme complex found in cells that participates in the citric acid cycle (also known as the Krebs cycle or TCA cycle) and is responsible for the conversion of alpha-ketoglutarate, a TCA cycle intermediate, to succinyl-CoA, another TCA cycle intermediate. The KGDH complex plays a key role in the generation of ATP (adenosine triphosphate) through the respiration process, which is widely used by cells to produce energy.
The KGDH complex is composed of three main components: E1 (alpha-ketoglutarate dehydrogenase), E2 (dihydrolipoyl succinyltransferase), and E3 (dihydrolipoamide dehydrogenase). Each of these components serves a specific function within the complex. E1 serves as a decarboxylase, removing a CO2 molecule from alpha-ketoglutarate to form the intermediate, succinyl-CoA. E2 accepts the acetyl group from the intermediate and transfers it to CoA-SH, forming acetyl-CoA. Finally, E3 regenerates the oxidized form of the E2 enzyme by transferring electrons to NAD+, producing NADH.
Various factors can regulate the activity of the KGDH complex, including the availability of substrates, allosteric effectors, and post-translational modifications. Allosteric effectors like ADP, ATP, NADH, and succinyl-CoA can modulate the activity of the KGDH complex, while post-translational modifications like phosphorylation and oxidation can also influence enzyme activity.
Overall, the KGDH complex is a critical enzyme complex that plays an essential role in the citric acid cycle and has a significant impact on the energy metabolism of cells.
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