BBMB 405 1nd Edition Lecture 15 Outline of Last Lecture XV Chapter 23 Protein Turnover and Amino Acid Catabolism B Proteins are degraded to amino acids C Protein Turnover is tightly regulated D The First step in amino acid degradation is the removal of nitrogen E Ammonium ion is converted into urea in most terrestrial vertebrates Outline of Current Lecture XV Chapter 23 Protein Turnover and Amino Acid Catabolism E Ammonium ion is converted into urea in most terrestrial vertebrates F Carbon atoms of degraded amino acids emerge as major metabolic intermediates Current Lecture XV Chapter 23 Protein Turnover and Amino Acid Catabolism E Ammonium ion is converted into urea in most terrestrial vertebrates 1 Overview went through in class will go through in more detail next lecture These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute 2 3 Make 35g day of urea 4 The urea cycle begins with formation of carbamoyl phosphate a Carbamoyl Phosphate synthatase 1 converts bicarbonate to carbamoyl phosphate b Glutamate is used to make ornithine cost ATP NADPH amino acid to alpha keto acid c Ornithine carbamoyl phosphate via ornithine transcarbamoylase citruline d Citruline aspartate via argininosuccinate synthetase argininosuccinate e Argininosuccinate via argininosuccinase arginine fumarate f Arginine via arginase ornithine urea 5 The urea cycle is linked to the citric acid cycle a Sum b Require 4 total high energy phosphates c When burn protein energy yield is 6 cal day gross in body yield is 4 cal day carbs because need some energy to make urea d Metabolic integration of nitrogen metabolism e 6 Urea cycle enzymes are evolutionarily related to enzymes in other metabolic pathways 7 Inherited defects of urea cycle cause hyperammonemia and can lead to brain damage errors of urea cycle a Argininosuccinase deficiency arg succ arg fumarate feed excess arginine left below b Carbamoyl phosphate synthetase deficiency CO2 NH3 carbamoylphosphate feed excess benzoate right above c Ornithine transcarbamoylase deficiency ornithine carbamoyl phosphate citrulline Pi feed excess phenylacetate d Minimize amino acid intake if don t have enzyme needed but less urea production 8 Urea is not only means of disposing excess nitrogen handout 2 13 F Carbon atoms of degraded amino acids emerge as major metabolic intermediates 1 Amino acids produce carbon skeletons that make intermediates of TCA cycle 2 Emphasize catabolism of Ala Ser Gly Asp AspNH2 Glut GlutNH2 Meth 3 Non glucogenic amino acids leucine lysine phenylalanine tryptophan tyrosine 4
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