TCA Cycle

TCA Cycle

1. Pyruvate

   • Acetyl-CoA
     • Citrate
       • cis-Aconitate
         • Isocitrate
           • alpha-ketoglutarate
             • Succinyl-CoA
               • Succinate
                 • Fumarate
                   • Malate
                     • OAA
                       • Aspartate & Asparagine
                         • Pyrimidines
                       • Phosphoenolpyruvate (PEP)
                         • Glucose
                         • Ser, Gly, Cys, Phe, Tyr, Trp
                     • Generated also by malic enzyme
                 • FADH2
               • Porphyrins, heme
               • GTP/ATP
               • Self-inhibiting/inhibits Acetyl-CoA formation
               • Gain of symmetry; cannot distinguish original acetyl
             • Glutamate
               • Purines
               • Arginine, Proline, Glutamine
           • NADH
             • Inhibits
           • NAD+ & Mn2+ required
         • Stereospecific; asymmetric binding
       • Fatty acids and sterols
         • Inhibit
       • Condensation reaction
   • Total cycle is doubled because there are 2 pyruvate
   • Pyruvate dehydrogenase complex
     • Coenzymes
       • TPP
       • Lipoate
       • NAD+
       • FAD
     • Substrate channeling

2. Regulation

   • ATP inhibits
   • ADP/AMP & Pi activate
   • Ca ions activate

3. Enzymatic processes involved

   • Dehydration/hydration
   • Transamination
   • Pyruvate dehydrogenase complex
   • Substrate level phosphorylation
   • Electron-carrier generators/redox
     • Oxidative decarboxylation
       • Removes CO2 irreversibly, usually taking a carboxyl
     • Dehydrogenation