Excessive amino acids are converted to NH₃ urea for excretion. Degradation of protein restores amino acid pools. Amino acids can also be used for gluconeogenesis, transamination, or deamination reactions. Transamination reactions are catalyzed by alanine aminotransferase (ALT) and aspartate aminotransferase (AST). All plasma proteins (except Igs and Hb) are synthesized in the liver. Neonates retain some hemoglobin synthesis. Metabolic pools of amino acids are maintained in the liver. Amino acids are protein building blocks. Under normal conditions, the rate of protein synthesis is equal to the rate of protein degradation. What are the metabolic functions of amino acids?
1) Conversion to NH₃ urea for excretion
2) Restoration of amino acid pools
3) Use in gluconeogenesis, transamination, or deamination reactions
4) Catalysis of transamination reactions by ALT and AST
5) Synthesis of plasma proteins in the liver
6) Retention of hemoglobin synthesis in neonates
7) Maintenance of metabolic pools of amino acids in the liver
8) Role as protein building blocks
9) Equal rates of protein synthesis and degradation
