Amino Acid Metabolism

Overview

• Focuses on how amino acids are metabolized and utilized for energy.
• Involves processes in the muscles and the liver.

Key Processes

Transamination

• Definition: Transfer of an amine group from an amino acid to a keto acid.
• Key Players:
  • Alanine: A primary amino acid in the process.
  • Alpha-ketoglutarate: A keto acid involved in the Krebs cycle.
  • Pyruvate: Formed from alanine after transamination.
  • Glutamate: Formed by the reaction of Alpha-ketoglutarate with an amine group.
• Enzymes:
  • Alanine Aminotransferase (ALT): Catalyzes the reaction between alanine and alpha-ketoglutarate.
  • Aspartate Aminotransferase (AST): Catalyzes reaction involving aspartate and alpha-ketoglutarate.
• Cofactors:
  • Pyridoxal phosphate: A derivative of vitamin B6, acts as a coenzyme in transamination.

Key Outcomes

• Alanine is converted into pyruvate.
• Pyruvate can be converted into:
  • Lactic acid in muscles (Cori cycle).
  • Acetyl-CoA for entry into the Krebs cycle and ATP production.
• Glutamate can be transported to the liver for further processing.

Oxidative Deamination

• Definition: Removal of an amine group from glutamate to produce ammonium ion.
• Enzyme: Glutamate Dehydrogenase.
• Significance: Produces NADPH, a reducing agent involved in fatty acid synthesis and free radical reactions.
• By-products:
  • Alpha-ketoglutarate is regenerated.
  • Ammonium ion: Toxic, hence converted into urea in the liver (urea cycle).

Significance of Amino Acid Metabolism

• Amino acids can be used for:
  • Energy production: Via Krebs cycle intermediaries and ATP production.
  • Gluconeogenesis: Formation of glucose from non-carbohydrate sources such as amino acids.

Clinical Relevance

• Enzyme markers:
  • Elevated AST and ALT levels can indicate liver or heart damage.
  • Used as diagnostic markers for myocardial infarction or liver disease.

Next Steps

• Further exploration into the Urea Cycle will follow in subsequent discussions.

This summary outlines the essential processes and enzymes involved in amino acid metabolism, focusing on transamination and oxidative deamination, and highlights the clinical relevance of these biochemical pathways.