The main contents of this chapter include all of the following: Protein metabolism, oxidation of amino acids, protein synthesis, catabolic-anabolic steady state, nutrient pools, amino acid pool, carbohydrate and fat pools, absorptive and postabsorptive states,. | 24 Nutrition, Metabolism, and Body Temperature Regulation: Part B Protein Metabolism When dietary protein is in excess, amino acids are Oxidized for energy Converted into fat for storage Oxidation of Amino Acids First deaminated; then converted into Pyruvic acid A keto acid intermediate of the Krebs cycle Events include transamination, oxidative deamination, and keto acid modification Figure Krebs cycle Oxidative deamination Transamination Amino acid + Keto acid (a-keto- glutaric acid) Keto acid + Amino acid (glutamic acid) Keto acid modification Modified keto acid Enter Krebs cycle in body cells Liver Kidney Blood During transamination an amine group is switched from an amino acid to a keto acid. During keto acid modification the keto acids formed during transamination are altered so they can easily enter the Krebs cycle pathways. NH3 (ammonia) Urea Urea In oxidative deamination, the amine group of glutamic acid is removed as ammonia and combined with CO2 to form urea. CO2 1 2 3 Excreted in urine Protein Synthesis Is hormonally controlled Requires a complete set of amino acids Essential amino acids must be provided in the diet Catabolic-Anabolic Steady State A dynamic state in which Organic molecules (except DNA) are continuously broken down and rebuilt Organs have different fuel preferences Nutrient Pools Three interconvertible pools Amino acids Carbohydrates Fats Amino Acid Pool Body’s total supply of free amino acids Source for Resynthesizing body proteins Forming amino acid derivatives Gluconeogenesis Figure Pool of carbohydrates and fats (carbohydrates fats) Dietary proteins and amino acids Food intake Some lost via cell sloughing, hair loss Excreted in urine Some lost via surface secretion, cell sloughing Excreted via lungs Dietary carbohydrates and lipids Urea Components of structural and functional proteins Nitrogen-containing derivatives (., hormones, neurotransmitters) Structural components of cells (membranes, etc.) Specialized . | 24 Nutrition, Metabolism, and Body Temperature Regulation: Part B Protein Metabolism When dietary protein is in excess, amino acids are Oxidized for energy Converted into fat for storage Oxidation of Amino Acids First deaminated; then converted into Pyruvic acid A keto acid intermediate of the Krebs cycle Events include transamination, oxidative deamination, and keto acid modification Figure Krebs cycle Oxidative deamination Transamination Amino acid + Keto acid (a-keto- glutaric acid) Keto acid + Amino acid (glutamic acid) Keto acid modification Modified keto acid Enter Krebs cycle in body cells Liver Kidney Blood During transamination an amine group is switched from an amino acid to a keto acid. During keto acid modification the keto acids formed during transamination are altered so they can easily enter the Krebs cycle pathways. NH3 (ammonia) Urea Urea In oxidative deamination, the amine group of glutamic acid is removed as ammonia and combined with CO2 to form urea. CO2 1 2
