Sciences_week_14_AA_UC.pdf

Amino Acid Metabolism & Urea Cycle  General principles of amino acid metabolism 1. Nutritionally nonessential amino acids are synthesized: 2. There are three general processes by which amino acids are catabolised: (i) by specific catabolic pathways; (ii) by conversion to other amino acids,...

Amino Acid Metabolism & Urea Cycle  General principles of amino acid metabolism 1. Nutritionally nonessential amino acids are synthesized: 2. There are three general processes by which amino acids are catabolised: (i) by specific catabolic pathways; (ii) by conversion to other amino acids, which are then catabolised by specific pathways; (iii) by a combination of transamination plus deamination, known as transdeamination.  NONESSENTIAL AMINO ACID BIOSYNTHESIS Nonessential Amino Acids may be formed: From Essential Amino Acids From Nonessential Amino Acids From Metabolic Intermediates Figure 15.6 The glycolytic pathway, divided into three stages. Textbook of Biochemistry with Clinical Correlations, 7e edited by Thomas M. Devlin © 2011 John Wiley & Sons, Inc. Amino Acid Transamination Figure 19.4 Alanine aminotransferase reaction. Textbook of Biochemistry with Clinical Correlations, 7e edited by Thomas M. Devlin © 2011 John Wiley & Sons, Inc.  Direct oxidative deamination (anaerobic) of only L-Glutamate Figure 19.13 Allosteric regulation of glutamate dehydrogenase. Textbook of Biochemistry with Clinical Correlations, 7e edited by Thomas M. Devlin © 2011 John Wiley & Sons, Inc.  D-amino acids are found in plants and cell walls of microorganisms, but are not used in the synthesis of mammalian proteins; D-amino acids are present in the diet and are metabolized by kidney and liver; 10  Amino Acid Catabolism Amphibolic intermediates are formed from the carbon skeletons of amino acids  Transamination of an amino acid with α-ketoglutarate Direct oxidative deamination of glutamate by glutamate dehydrogenase Figure 19.21 Synthesis of carbamoyl phosphate and entry into urea cycle. Textbook of Biochemistry with Clinical Correlations, 7e edited by Thomas M. Devlin © 2011 John Wiley & Sons, Inc. Arginine produces Nitric oxide (NO) (mediator of vasodilation in blood vessels.); Serotonine and Melatonin are produced after Tryptophan (Serotonine is a potent vasoconstrictor and stimulator of smooth muscle contraction.); Glycine in involved in Heme synthesis; Glutamine, Aspartate, Glycine, contribute in Nucleotide synthesis; Derivatives of Methionine in involved in DNA metabolism; Tyrosine is used in melanine (pigment) synthesis; Glycine, Glutamate, Glutamine are neurotrasmitters Conversion of Tyrosine to Dopamine, Epinephrine and Norepinephrine Figure 19.10 Pyridoxal-phosphate-dependent-reactions. Textbook of Biochemistry with Clinical Correlations, 7e edited by Thomas M. Devlin © 2011 John Wiley & Sons, Inc. Reaction catalyzed by Histidine pyridoxal phosphate-dependent Decarboxilase Blood vessel dilation or constriction depending on receptor; Allergic reactions...