Expanded TCA cycle (TriCarboxylic Acid Cycle, aka Citric Acid Cycle, aka Krebs cycle)

DOI: 10.5281/zenodo.13369827 Oxaloacetate Citrate Isocitrate α-ketoglutarate Succinyl-CoA Succinate Fumarate MalateMalate Acetyl-CoA citrate synthase isocitrate dehydrogenase NAD+ NADH GTP FADH2 CO2 NADH aconitase α-ketoglutarate dehydrogenase complex CoA CoA succinyl-CoA synthetase GDP + Pi FAD succinate dehydrogenase (CII of the ETC) H2O NAD+malate dehydrogenase CoA fumarase NAD+ CO2 NADH Pyruvate Lactate fatty acids, ketone bodies NAD+ CO2 NADH CO2 Glucose pyruvate dehydrogenase ⓍATP, acetyl-CoA, NADH, fatty acids AMP, CoA, NAD+, Ca2+, insulin Glycogen ⓍATP, succinyl-CoA, NADH, citrate ADP ⓍATP ADP, Ca2+ Ⓧsuccinyl-CoA, NADH Ca2+ Citrate can be removed from mitochondria for lipid synthesis Malate can be removed from mitochondria for synthesis of glucose & some amino acids. NAD+ NADH lactate dehydrogenase pyruvate carboxylase ATP ADP + Pi TriCarboxylic Acid cycle aka citric acid cycle, Krebs cycle ATP citrate lyase aspartate transaminase* malic enzyme CoA ATP ADP + Pi Oxaloacetate NAD+ NADH malate dehydrogenase Oxaloacetate Acetyl-CoA fatty acids, ketone bodies NADPH NADP+ CO2 Citrate Phosphoenolpyruvate GTP GDP CO2 various transaminases amino acid α-keto acid glutamate α-Ketoglutarate Glutamate Aspartate This AST reaction can also happen in the mitochondria, but there’s not enough space in the diagram to depict it there, sorry! glutamine Glutamine is the main amino acid used to replenish the TCA cycle. Many fates to choose from! Alanine alanine transaminase α-ketoglutarate glutamate odd chain fatty acids PEP carboxykinase QQH2 protein acetylation aspartate, PEP, malate gluconeogenesis glutamate dehydrogenase NAD+ NH4+NADH acetyl-CoA CoA H2O *aspartate transaminase is aka aspartate aminotransferase and glutamic-oxaloacetic transaminase (GOT) Or, it can be brought into the mitochondria as part of the malate-aspartate shuttle for transporting NADH equivalents into the mitochondria.