1. Nitrogen Cycle

3. Summary of Protein and Amino Acid Metabolism

6. Transamination Common acceptors:  -ketoglutarate (glutamate) pyruvate (alanine); oxaloacetate (aspartate) Important transaminases: Aspartate transaminase (AST) (also called glutamate-oxaloacetate transaminase, GOT) High activity in heart; tool for diagnosis of heart damage (transaminase) Alanine transaminase (ALT) (also called glutamate-pyruvate transaminase, GPT) High activity in liver; tool for diagnosis of liver damage

7. Oxidative Deamination

8. Alanine – Glucose Cycle

9. Urea Cycle

10. The Urea Cycle glutamine (from extrahepatic tissues) ornithine carbamoyl phosphate H 2 N C OPO 3 2– O alanine ( from muscle)  -ketoglutarate pyruvate glutamate glutamine glutamate NH 4 + oxaloacetate aspartate  -ketoglutarate aspartate 2 ATP 2 ADP + P i HCO 3 – citrulline PiPi arginosuccinate 2P i ATP AMP fumarate arginine urea H 2 N C NH 2 O ornithine H2OH2O malate NADH NAD +  -ketoglutarate mitochondrial matrix cytosol malate H2OH2O

11. Fate of Carbon Atoms from Amino Acids Tryptophan glucogenic amino acids ketogenic amino acids

12. Biosynthesis of Nonessential Amino Acids Methionine (essential amino acid)

13. Amino Acids as Precursors of Other Nitrogeneous Compounds Amino Acid Product(s) GlycineHeme, Purines TyrosineThyroid Hormones Epinephrine Dopamine Melanin HistidineHistamine SeratoninTryptophan AspartatePurines, Pyrimidines GABA (gamma-aminobutyrate) Glutamate