This preview shows page 1. Sign up to view the full content.
Unformatted text preview: an be a significant source of energy! This varies depending the type of organism and metabolic conditions. The amino groups and the carbon skeleton take separate but interconnected pathways! Because only few organisms can produce NH3 from N2, amino groups are carefully husbanded in biological systems. Chap.18 Chap.16 Chap.14 A. Metabolic fates of amino-acids 1. Enzymatic degradation of dietary proteins • • Pepsin cuts protein into peptides in the stomach. Trypsin and chymotrypsin cut proteins and larger peptides into smaller peptides in the small intestine. Aminopeptidase and carboxypeptidases A and B degrade peptides into amino acids in the small intestine. • 2 2. Amino group catabolism (overview from vertebrate liver)
Most of the ammonia formed in vertebrates is transported as Glu, Gln or Alanine . Ammonia is eliminated as ammonia, urea (Chap. 18) or/and uric acid (Chap.22)
Aminotransferase PLP Glu dehydrogenase Glutaminase In human and great apes, excess of nitrogen is eliminated as urea (from aas ) and uric acid (from purines ) 3. The glucose-...
View Full Document