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The Citric Acid Cycle - Coggle Diagram

- - - - The only reaction with C-C bond formation
      - Rate-limiting step of CAC
      - Activity largely depends on [oxaloacetate].
  - - - Elimination of H2O
      - Citrate is poor substrate for oxidation
      - Isocitrate is a good substrate for oxidation.
  - - - carbons not directly from glucose because carbons lost came from
        oxaloacetate, not acetate
      - Succinyl-CoA is another higher-energy thioester bond.
  - - - Substrate-level phosphorylation
      - incorporation of inorganic phosphate
      - Produces GTP
  - - - Bound to mitochondrial inner membrane
      - Reduction of the alkane to alkene requires FADH2
  - - - Stereospecific
  - - - Regenerates oxaloacetate for citrate synthase
      - UNfavorable/reversible
        
        oxaloacetate concentration kept VERY low by citrate synthase
- - - - occurs in the cytoplasm
      - Conversion of Pyruvate to Acetyl-CoA
        
        Catalyzed by the pyruvate dehydrogenase complex
        
        TPP, lipoyllysine, and FAD are prosthetic groups
        
        NAD+ and CoA-SH are co-substrates.
        
        PDC is a large (up to 10 MDa) multienzyme complex.
        
        pyruvate dehydrogenase (E1)
        
        Step 1: Decarboxylation of pyruvate to an aldehyde
        
        Step 2: Oxidation of aldehyde to a carboxylic acid
        
        dihydrolipoyl transacetylase (E2)
        
        Step 3: Formation of acetyl-CoA (product 1)
        
        dihydrolipoyl dehydrogenase (E3)
        
        Step 4: Reoxidation of the lipoamide cofactor
        
        Step 5: Regeneration of the oxidized FAD cofactor
        
        forming NADH (product 2)
        
        Channeling minimizes side reactions
  - - - in the mitochondrial matrix
  - - - in the inner membrane