BBMB 405 1nd Edition Lecture 15 Outline of Last Lecture XV. Chapter 23: Protein Turnover and Amino Acid CatabolismB. Proteins are degraded to amino acidsC. Protein Turnover is tightly regulatedD. The First step in amino acid degradation is the removal of nitrogenE. Ammonium ion is converted into urea in most terrestrial vertebratesOutline of Current Lecture XV. Chapter 23: Protein Turnover and Amino Acid CatabolismE. Ammonium ion is converted into urea in most terrestrial vertebratesF. Carbon atoms of degraded amino acids emerge as major metabolic intermediatesCurrent LectureXV. Chapter 23: Protein Turnover and Amino Acid CatabolismE. Ammonium ion is converted into urea in most terrestrial vertebrates1. 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 urea4. The urea cycle begins with formation of carbamoyl phosphatea. Carbamoyl Phosphate synthatase 1 converts bicarbonate to carbamoyl phosphateb. Glutamate is used to make ornithine, cost: ATP, NADPH, amino acid to alpha keto acidc. Ornithine + carbamoyl phosphate via ornithine transcarbamoylase citrulined. Citruline + aspartate via argininosuccinate synthetase argininosuccinatee. Argininosuccinate via argininosuccinase arginine + fumaratef. Arginine via arginase ornithine + urea5. The urea cycle is linked to the citric acid cyclea. Sum: b. Require 4 total high energy phosphatesc. When burn protein energy yield is 6 cal/day (gross), in body yield is 4 cal/day (carbs) because need some energy to make uread. Metabolic integration of nitrogen metabolisme.6. Urea cycle enzymes are evolutionarily related to enzymes in other metabolic pathways7. 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 carbamoyl-phosphate), feed excess benzoate (right, above)c. Ornithine transcarbamoylase deficiency: (ornithine + carbamoyl-phosphate citrulline + Pi), feed excess phenylacetated. Minimize amino acid intake if don’t have enzyme needed, but less urea production8. Urea is not only means of disposing excess nitrogen (handout 2/13)F. Carbon atoms of degraded amino acids emerge as major metabolic intermediates1. Amino acids produce carbon skeletons that make intermediates of TCA cycle2. Emphasize catabolism of Ala, Ser, Gly, Asp, AspNH2, Glut, GlutNH2, Meth3. Non glucogenic amino acids: leucine, lysine, phenylalanine, tryptophan,
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