Substrate based inhibitors of Strawberry Dioxygenase: Homology Models

The stereoselective oxidation of an unreactive alkane C-H bond is most often carried out by monoxygenases or oxygenases including dioxygenases which use iron as a cofactor and constitute a family of enzymes, e.g. Redox enzymes. A dioxygenase is an enzyme which incorporates both the atoms of molecular oxygen into kinds of substrates. The oxidative transformation reactions are common reactions during fruit ripening and Abscisic acid biosynthesis in strawberries. The main substrate of 2-OG (oxoglutarate) dependent dioxygenases is glutarate which is converted in succinate during flavor biogenesis. The dioxygenase currently studied belongs to 9-cisepoxycarotenoid dioxygenases (NCEDs), which catalyzes the final step in Abscisic acid biosynthesis. Oxidative reactions catalyzed by 2-OG dependent dioxygenases are important mechanistic steps in the biosynthesis of variety of metabolites in plants as well as mammals, including flavor compounds and materials of medicinal and agrochemical importance, such as plant hormones e.g. gibberellins and abscisic acid, and antibiotics such as cepahlosporin and β-lactamase inhibitor clavulanic acid. Members of carotenoid cleavage dioxygenases (CCDs) family catalyze the oxidative cleavage of carotenoids at various chain positions leading to the formation of a wide range of apocarotenoid signaling molecule. Here, we report a selective inhibition of strawberry dioxygenase and assume that these inhibitor compounds can resolve functions of this diverse enzyme family. To explore the possibilities we have used a chemical approach to select designed inhibitors for different classes of carotenoid cleavage dioxygenases. We have used substrate based inhibitors such as oxoglutarate analogue CyclohexanedioneCa, Abamine derivative BAS8769 (N-[4-(4Fluoro-phenyl)-thiazol-2-yl]-benzene-1, 4-diamine) and Dicamba which contains benzyl-aryl, cyclohexanone and benzoyl ring moieties respectively. We hypothesize that these are potent dioxygenase inhibitors and selectively inhibit dioxygenase enzymes that cleave carotenoids at 9,10,11,12 positions and also 2-oxoglutarate dependent dioxygenases e.g. 4hydroxyphenylpyruvate dioxygenases (HPPDs).