Catabolism of Amino Acids

CATABOLISM OF AMINOACIOS catabolism of aminoacids involves the catabolism of amine Skeletonmo group and the catabolism of theire carbon The excess dietary amino acids are neithere stored. For future use non excreted. Rathere the Sureplus aminoacids undergo catabolism. →Duning catabolism firest amino groups of sureplus amino acids ane removed, convented to Unea and excreted via the unine. →The remaining carbon skeletons becomes the corresponding 2. Keto acids acids can eithere be Con and 1120 to The fate of X-keto completely oxidized into gemercate ATP Removal of aminogroup from amim acids can be achieved by following process. A) Trans amination. B) Deamination. A) Treans ammination: →Treansamination is a process of transfen of the Qamino group from an amino acid to an giketo. acid which results in the formation of a new amino acid →Transamination mostly occurs in the livere, heart muscle, skeletal muscle and Kidney. → Treans amination reactions are reversible processes catalyzed by aminotransferase. All aminotransferase contain coenzyme pyrin 5-phosphate (PLP),covalently binds at thein catalytic site via a Schiff base is formed 4 amino acid. Schift base linkage. The by the amine component Substrate and the PLP. The role of PLP camrien carbonyl component ts to serve as a مد of amino groups. Mechanism of Transamination →Aminotransferase amino acids a Keto acid by The Mechanism amino groups from remove a trans tenning thein amim groups to of PLP catalyzed treansamination in two stages consists of three steps each. Step-x [conversion of an aminoacid to X-keto acid] 1. Transamination: absence of amino acid, the aldehyde group of PLP is in Schiff base linkage with amino group of the lysine residue of the enzyme Forming an interinal ablimine A new Schiff base is formed. on the addition of an amino acid substrate (AA-1). The amino group of AA's attacks the carbon atom of în terinal aldimine in a transamination reaction external aldimine. to form Step- [convension of an a-keto acid to an amino acid In the second half of the transamination reaction that occure by the neversal of the above pathway in which pmp converted back enzyme pup schift base complex. These three reversible steps ane to A new d-keto aud-2 which to the second Saubstrate niw reacts with pmp to fonma new schitt base ketimine 2- The ketimine is then tautomenizes into aldimine. 9= the attemine is fimally cleaved to nelease amino acid, as the second product. while the active site lysine regenenate's the original enzyme php schift bage. a keto acidz + EPMP Amino Acid-2 + E-PLP. Significance of transamination 1. It helps in degradation of suteplus amim auds. 2. Helps in the synthesis of essential amim acids, 3- Pruducer gluconeogenic products such as Peyravate and oxalacetate. DEAMINATION →Deamination is the Process of removal amino groups from amino acids... In the human deamination takes place body.d Primarily in the livere and > Deamination may occure Kidney by towo processes ie I) oxidative deamination. J Non-oxidative deamination. 1) Oxidative deamination: During oxidative deamination glutamate catalyzed by glutamate dehydrogenase forming a-ketoglutarcate and ammonia. →The glutamate dehydrogenase is a mitochondrial enzyme that uses agents like NAD+ oxidizing on NADP+ to NADHZ OR NADPH respectively. The enzyme is stimulated by ADP/GDP Glutamate +NAD/NADPH -ketoglutarate. + Ammonia Glutamat ADP/GOP NADIL NADPH Ⅱ) Non-oxidative deamination: It is a type of deamination reaction in which the removal amine group through an occurs without proceeding oxidation reaction. Howevere this type of deamination reactions liberak ammonia producing the corresponding a-keto acids to → Amino acids like senine Thneo nine ane directly deaminated by the non-oxida Process. ane The non-oxidative de aminations. catalyzed by dehydratase Serine sereine dehydratase, Pyruvate + NH3. Threonine Threonine dehydratase, a-keto butyrate