1. Amino Acid Metabolism

2. Essential Amino Acids Essential amino acids must be consumed in the diet. Mammalian cells lack enzymes to synthesize their carbon skeletons (  -keto acids). These include: Isoleucine, leucine, & valine Lysine Threonine Tryptophan Phenylalanine (Tyr can be made from Phe.) Methionine (Cys can be made from Met.) Histidine (Essential for infants.)

4. Reductive amination catalyzed by glutamate dehydrogenase

5. Glutamine synthesis is coupled to hydrolysis of ATP

6. Pyruvate is an amphibolic intermediate in synthesis of alanine

7. Asparagine synthesis is energetically favorable due to coupling to ATP hydrolysis

8. Serine biosynthesis

9. Multistep pathway for glycine biosynthesis

10. Glycine is also synthesized from serine

11. Proline biosynthesis

12. Cysteine is not nutritionally essential, however it is derived from methionine

13. Tyrosine is formed from phenylalanine

14. Hydroxyproline is formed after protein synthesis

15. Selenocysteine is synthesized from serine and selenophosphate

16. Amino acids that are synthesized de novo in humans. All are related by a small number of steps to glycolysis or TCA cycle intermediates.

17. Salvage pathways for formation of certain nonessential amino acids from other amino acids Amino Acid formedPrecursor Amino Acid ArginineProline CysteineMethionine TyrosinePhenylalanine