Question

2. a) The plant hormone indole acetic acid (IAA) is biosynthesized from the amino acid tryptophan as shown below. The enzyme for the first step is an aminotransferase that utilizes pyridoxal and a- ketoglutarate. Draw a plausible arrow-pushing mechanism for this reaction. b) The second step uses a flavin-dependent enzyme. Starting from a reduced flavin (FADH2) and O2 draw a plausible arrow-pushing mechanism for the decarboxylation and oxidation of indole-3-pyruvate to indole acetic acid OOH NH2 OH Trp indole-3-pyruvate indole acetic acid (IAA)

Answer 1

WWW liven OH i on aminotrcond lenje flovin dependent ename. Ondole -3- Pyruvate Тір. Incole (Amino aud) (IPA) authcaud (Inn) Mechanism of Reaction :- Armino transferases are enzymes that catalyse a transamination reaction between an amino acid and an d-keto acid. I Å The first step is catalysed by TAAS that transfer the anino group from Tryptophan to an alpha keto acid such as byruvate to generate TPA and another amino acids. одн COOH COOH COOH TAA IPA Tryptophane Aminotransfer ase of Arabidopsis in I In and seep The second step is an oxygen and NADPH -dependent reaction Catalysed by the Yuc flawin - containing mono oxygenases. Coor (Naopajtos Coutes BIT B yoc yuc o IPA NADPH > Nicotinamiche Qdenine dinucleotide phosphate ( H B Tg . 9020 ge-transfer 0²0 oxygen. - HT + 80=0 + Proton Ruper Oxicle radical no NADPH or Nha * represents Because of complex &t pt represents half str of NADPH NADPM

vyvUUUUUUUUUUUUUUUUUUUUUU Overall . NADPH + Og - H+ + 6 mom + NADP+ — " + whoe? radio anion To go i to u to. one op which is missing there is DC-DH m o Decorboxylation Indole - 3- Ocht Oldehyell Oxidised by NACPH Ep Og as NO thul this Indole — 3- acetaldeaple NADPH OH quos tamen FADH & ii also used as oridation NA half flawin pupresunt 1x OA redical anion free radical Subscoti HHO-OH - OH Hó In masina ofoare Product

whole Oxn represent as Dion ROH Ethn ing transfer ou 25 Decalboxylati -102 I on Oxidation FADH a toa End producto