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. Author manuscript; available in PMC: 2020 Dec 1.
Published in final edited form as: Mol Genet Metab. 2019 Oct 17;128(4):444–451. doi: 10.1016/j.ymgme.2019.10.007

Figure 1: TCA cycle and Propionate Pathway.

Figure 1:

A diagram of the TCA cycle showing its intermediates and energy sources. TCA is fed by the propionate pathway, glycolysis and fatty acid oxidation (via acetyl-CoA) which all help to maintain TCA intermediates. The propionate pathway is characterized by production of propionyl-CoA and is involved in metabolism of cholesterol, valine, odd chain fatty acids, methionine, isoleucine and threonine (c-VOMIT). Mut is the last step in the propionate pathway and feeds succinyl-CoA into the TCA cycle. Here, the intermediates and enzymes of interest (boxed and capitalized) are listed. Two known “toxins”, 2-methylcitrate and 3-hydroxypropionate are also illustrated. Abbreviations: CS (citrate synthase), aconitase 2 (ACO2), isocitrate dehydrogenase 2/3 (IDH2/3), 2-oxoglutarate dehydrogenase complex (OGDHc), succinate synthase (SS), succinyl-CoA synthetase (SCS), methylmalonyl-CoA mutase (MUT), propionyl-CoA carboxylase (PCC), c-VOMIT (cholesterol, valine, odd chain fatty acids, methionine, isoleucine, threonine), succinate dehydrogenase (SDH), fumarate hydratase (FH), malate dehydrogenase 2 (MDH2), 2-methycitrate (2-MC), 3-hydroxypropionic acid (3-OH PA)