Synthesis of Glucose From Amino Acids.

Synthesis of Glucose from Amino Acids (Gluconeogenesis)

Definition:

• Conversion of glucogenic amino acids to glucose via the gluconeogenesis pathway in the liver (mainly) and renal cortex.

• Process:

  1. Glucogenic amino acids (e.g., alanine, glutamine) are deaminated → produce pyruvate or TCA cycle intermediates (e.g., oxaloacetate).

  2. Intermediates enter gluconeogenesis → converted to glucose.

• Key Enzymes:

  • Pyruvate carboxylase (Pyruvate → Oxaloacetate) – requires biotin & ATP

  • Phosphoenolpyruvate carboxykinase (PEPCK) (Oxaloacetate → PEP) – requires GTP

• Example:
  Alanine–glucose cycle →
  Alanine → Pyruvate → Glucose → Blood → Muscle.

• Energy cost: 6 ATP (per glucose molecule synthesized).