TRANSDEAMINATION AND DEAMINATION

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TRANSDEAMINATION
TRANSAMINATION
DEAMINATION

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TRANSDEAMINATION AND DEAMINATION

  1. 1. TRANSDEAMINATION AND DEAMINATION By: Minhaz Ahmed BBI11014 Int msc V sem Tezpur university Assam
  2. 2. CONTENT • TRANSDEAMINATION • TRANSAMINATION • DEAMINATION
  3. 3. TRANSDEAMINATION The amino group of amino acids is released by a coupled reaction, TRANSDEAMINATION Transamination followed by oxidative deamination. Transamination takes place in the cytoplasm of all the cells of the body : the amino group is transported to liver as glutamic acid, which is finally oxidatively deaminated in the mitochondria of hepatocytes. Thus, the two components of the reaction are physically far away, but phisiologically they are coupled. Hence, Transdeamination.
  4. 4. • Transamination is a chemical reaction between two molecules. • One is an amino acid, which contains an amine (NH2) group. • The other is a keto acid, which contains a keto (=O) group. • In transamination, the NH2 group on one molecule is exchanged with the =O group on the other molecule. The amino acid becomes a keto acid, and the keto acid becomes an amino acid. • Transamination in biochemistry is accomplished by enzymes called transaminases or aminotransferases.
  5. 5. 5 Transamination transfer of -NH2 group from one substrate to other • most AA (not Lys, Thr, Pro, His, Trp, Arg, Met) • amino group is transferred from AA to 2-oxoglutarate • cofactor – pyridoxal phosphate (→ Schiff bases) • reversible reaction ⇒ important for synthesis of AA
  6. 6. 6 General scheme of transamination CH2CH2COOH O CHOOC+R CH NH2 COOH aminokyselina 2-oxoglutarát HOOC CH CH2CH2COOH NH2 +R C O COOH glutamát2-oxokyselina aminotransferasa pyridoxalfosfát amino acid 2-oxo acid 2-oxoglutarate glutamate aminotransferase pyridoxal phosphate
  7. 7. DEAMINATION • Deamination is the removal of an amine group from a molecule. Enzymes which catalyse this reaction are called deaminases. • In the human body, deamination takes place primarily in the liver, however glutamate is also deaminated in the kidneys. • Deamination is the process by which amino acids are broken down if there is an excess of protein intake. The amino group is removed from the amino acid and converted to ammonia.
  8. 8. Deamination of amino acids •Deamination - elimination of amino group from amino acid with ammonia formation. • Four types of deamination: • - oxidative (the most important for higher animals), • - reduction, • - hydrolytic, and • - intramolecular
  9. 9. Reduction deamination: R-CH(NH2)-COOH + 2H+ → R-CH2-COOH + NH3 amino acid fatty acid Hydrolytic deamination: R-CH(NH2)-COOH + H2O → R-CH(OH)-COOH + NH3 amino acid hydroxyacid Intramolecular deamination: R-CH(NH2)-COOH → R-CH-CH-COOH + NH3 amino acid unsaturated fatty acid
  10. 10.  During oxidative deamination, an amino acid is  converted into the corresponding keto acid by the  removal of the amine functional group as ammonia.  The amine functional group is replaced by the ketone  group. The ammonia eventually goes into the urea  cycle.  Oxidative deamination occurs primarily on glutamic  acid because glutamic acid was the end product of  many transamination reactions.  The glutamate dehydrogenase is controlled by ATP and  ADP. ATP acts as an inhibitor whereas ADP is an  activator.
  11. 11. 12 Proteins NH3 glutamate glutamate + urea (excretion by urine) 2-oxoglutarate + glutamine proteolysis dehydrogenation + deamination detoxication in liver deamidation in kidney amino acids transamination detoxication in other tissues NH4 + (excretion by urine) NH4 + (excretion by urine) deamination in kidney Intake, catabolism, and excretion of nitrogen
  12. 12. THANK YOU

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