The tricarboxylic acid (TCA) cycle is a system of enzymes in the mitochondrial matrix (and succinate dehydrogenase in the inner mt-membrane) arranged in a cyclic metabolic structure, including dehydrogenases that converge in the NADH pool and succinate dehydrogenase for entry into the ETS. Citrate synthase is a marker enzyme of the TCA cycle, at the gateway into the cycle from pyruvate via acteyl-CoA. Sections of TCA cycle are required for Ξ²-oxidation. Anaplerotic reactions fuel the TCA cycle with other intermediary metabolites. In the cell, the TCA cycle serves biosynthetic functions by metabolite export from the matrix into the cytosol.
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