BIOC13H3 Lecture Notes - Lecture 12: Essential Amino Acid, Creatine Kinase, Aspartate Transaminase
Document Summary
Bioc13winter2013 lecture 12: amino acid metabolism and metabolic integration. Amino acid metabolism: plants and bacteria synthesize all twenty amino acids, humans can only synthesize about half of the twenty amino acids (non-essential aas). In general, the more complex amino acids are essential amino acids in humans as they require enzymes that have been lost from the human genome over evolutionary time. Protein degradation: free amino acids in the body can be generated by degradation of cellular proteins which occurs continuously in all cells. In order for proteins to be degraded by the proteasome, they are first tagged on lysine residues by covalent linkage of ubiquitin. Ubiquitin is a 76 amino acid protein found in all eukaryotic cells that is specifically attached to proteins by ubiquitin ligating enzymes: the proteins are cleaved by endo and exo-proteases/peptidases to individual amino acids. The urea cycle: glutamate and glutamine function as the primary nitrogen carriers in most organisms.
