ACETATE PATHWAY

The glyoxylate cycle, a variation of the tricarboxylic acid cycle, is an anabolic pathway occurring in plants,

  1. Condensation of acetyl-CoA with oxaloacetate to form citrate:
    • Acetyl-CoA produced either from acetate or by β-oxidation of fatty acids enters into TCA cycle and is condensed with oxaloacetate to form citrate.
  2. Isomerization of citrate to isocitrate:
    • Citrate is isomerized to isocitrate in TCA cycle.
  3. Cleavage of isocitrate to from succinate and glyoxylate:
    • This is the bypass reaction of TCA cycle.
    • here, isocitrate is cleaved by isocitrate lyase to form succinate and glyoxylate.
  4. Condensation of glyoxylate with acetyl-CoA to yield malate:
    • Succinate is further metabolized by TCA cycle.
    • Glyoxylate then condenses with a second molecule of acetyl-CoA to form malate catalyzed by malate synthase.
  5. Oxidation of malate to form oxaloacetate:
    • Malate is oxidized subsequently to oxaloacetate by the enzyme malate dehydrogenase.
    • Oxaloacetate then starts another turn of the cycle.

Significance 

  1. Fatty acid Synthesis
  2. Glucose production from non-carbohydrate source (Neoglucogenesis) 
  3. ATP production 



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