Find research datasets worth reusing

Fig. 14 in The scope of flavin-dependent reactions and processes in the model plant Arabidopsis thaliana

Fig. 14. Reduction of nitrate to nitrite at the expense of NAD(P)H. After reduction of the Moco, nitrate displaces the hydroxyl group bound to the molybdenum atom and is directly reduced to nitrite (for mechanistic details see Hille, 2013). Nitrite can also be reduced to nitric oxide involving a one-electron reduction. However, the mechanism of this reaction is currently unknown.

Fig. 25 in The scope of flavin-dependent reactions and processes in the model plant Arabidopsis thaliana

Fig. 25. Reaction catalyzed by 4′-phosphopantothenoylcysteine decarboxylase. The enzyme uses non-covalently bound FMN, which is transiently reduced in the first half-reaction (substrate oxidation) yielding a thioaldehyde intermediate (top). At this stage, decarboxylation occurs (right) and the generated enethiolate is then subject to reduction to the final product 4′-phosphopantetheine (bottom). Thus the flavin serves as a transient electron sink during the decarboxylation reaction.

Fig. 9 in The scope of flavin-dependent reactions and processes in the model plant Arabidopsis thaliana

Fig. 9. The first step of proline degradation. Proline dehydrogenase 1 and 2 catalyze the two-electron oxidation of the C–N bond in the pyrollidine-ring as shown. The enzymes are peripherally associated with the inner mitochondrial membrane enabling direct transfer of the electrons to CoQ.

Fig. 11 in The scope of flavin-dependent reactions and processes in the model plant Arabidopsis thaliana

Fig. 11. Reactions catalyzed by xanthine dehydrogenase. The enzyme oxidizes hypoxanthine to xanthine and further to uric acid. The initial oxidation occurs at the Moco and electrons are transferred to two iron-sulfur-complexes operating in-line to reduce the FAD cofactor, which in turn reduces NAD+ to NADH. Alternatively, the enzyme may reduce dioxygen either to hydrogen peroxide or superoxide when present in its oxidase conformation. The oxygen atom incorporated in the products is derived from water (shown in red, for details of the reaction mechanism, see Nishino et al., 2013). (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)

Fig. 4 in The scope of flavin-dependent reactions and processes in the model plant Arabidopsis thaliana

Fig. 4. Reaction catalyzed by the lipoamide dehydrogenase subunit (E3). This subunit is present in the pyruvate, α-ketoglutarate and branched-chain α-keto acid dehydrogenase complex where the dithiol of the lipoamide moiety first reduces the internal disulfide bridge (top) and subsequently the reduced internal dithiol reduces the FAD (right), which in turn reduces NAD+ (left) leading to the resting state of the enzyme.

Fig. 22 in The scope of flavin-dependent reactions and processes in the model plant Arabidopsis thaliana

Fig. 22. Reactions catalyzed by pyridoxamine/pyridine 5′-phosphate oxidase. The enzyme accepts pyridoxamine and pyridoxine 5′-phosphate as substrate. The oxidation of pyridoxamine 5-phosphate leads to the imine, which is hydrolyzed to the aldehyde and ammonia (upper curved arrow). In both reactions the reduced cofactor FMN is re-oxidized by dioxygen resulting in the generation of hydrogen peroxide (upper and lower curved arrow).

Fig. 3 in The scope of flavin-dependent reactions and processes in the model plant Arabidopsis thaliana

Fig. 3. Oxidation of succinate to fumarate catalyzed by succinate dehydrogenase (complex II). The reduced FAD donates the electrons to a pair of iron-sulfur clusters from where they are finally delivered to a cytochrome leading to the reduction of ubiquinone (CoQ) in the inner mitochondrial membrane.

Fig. 6 in The scope of flavin-dependent reactions and processes in the model plant Arabidopsis thaliana

Fig. 6. Reaction catalyzed by D-lactate dehydrogenase. The reduced FAD cofactor is reoxidized by cytochrome c in the intermembrane space of mitochondria and the electrons are transferred to cytochrome c oxidase (complex IV) of the mETC.

Fig. 2 in The scope of flavin-dependent reactions and processes in the model plant Arabidopsis thaliana

Fig. 2. Biosynthesis of riboflavin in A. thaliana. The biosynthesis of riboflavin starts with GTP (top left), which is converted in four enzymatic steps to 5-amino-6- ribityl-aminouracil (center). The second component needed is D-ribulose-5-phosphate (center, left), which is converted to 3,4-dihydroxy-2-butanone-4-phosphate (shown in blue). The second ring is generated by condensation of the two intermediates, a reaction catalyzed by lumazine synthase (RibE) yielding 6,7-dimethyl- 8-ribityl lumazine. The last step of the biosynthesis is a dismutation reaction involving two lumazine molecules resulting in the generation of riboflavin and 5- amino-6-ribityl-aminouracil, which reenters riboflavin biosynthesis. For clarity, the two lumazine molecules are highlighted in red/blue and red/green, respectively. The double headed green arrow (top, right) indicates the swap of reactions compared to riboflavin biosynthesis in E. coli and S. cerevisiae. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)

Fig. 42 in The scope of flavin-dependent reactions and processes in the model plant Arabidopsis thaliana

Fig. 42. Reaction catalyzed by monolignol oxidoreductases. The enzymes were shown to accept monolignols with different substitution patterns in the aromatic ring (R1 and R2 = H, p-coumaryl alcohol; R1 = H and R2 = methoxy, coniferyl alcohol; R1 and R2 = methoxy, sinapyl alcohol) (Daniel et al., 2015). In contrast to the other members of the BBE-like enzyme family, most of the enzymes catalyzing this reaction are dehydrogenases, with the exception of AtBBE24 (Zafred et al., 2015). The electron acceptor for the dehydogenases is yet unknown.

Fig. 20 in The scope of flavin-dependent reactions and processes in the model plant Arabidopsis thaliana

Fig. 20. Two flavoenzymes involved in ascorbate biosynthesis and maintenance. L-Galactono-1,4-lacton dehydrogenase catalyzes the last step in the Smirnoff-Wheeler pathway to yield ascorbate from L-galactono-1,4-lactone (top). The substrate-derived electrons are passed on to cytochrome c and thus enter the mETC. The detoxification of ROS or ferric iron leads to the generation of the monodehydroascorbate radical (right), which is recycled to ascorbate by the action of monodehydroascorbate dehydrogenase (left-center). For details of the latter reaction see text.

Fig. 44 in The scope of flavin-dependent reactions and processes in the model plant Arabidopsis thaliana

Fig. 44. Reaction of flavin-containing monooxygenases (clade 3). The seven enzymes characterized so far were all shown to be S-glucosinolate oxidases that catalyze the S-monooxygenation of methylthioalkyl glucosinolates to the corresponding methylsulfinyl glucosinolates (Hansen et al., 2007; Kong et al., 2016; Li et al., 2008). For the nine uncharacterized members a similar catalytic function is hypothesized, but remains to be confirmed.

Fig. 23 in The scope of flavin-dependent reactions and processes in the model plant Arabidopsis thaliana

Fig. 23. Reaction catalyzed by NDC1/demethylphylloquinone reductase. The penultimate step in the biosynthesis of phylloquinol affords demethylphylloquinol by two-electron reduction of the demetyhlphylloquinone (top reaction). Through nucleophilic attack of the aromatic ring onto the methyl group (in red) of SAM the final methylated product, phylloquinol is formed and S-adenosylhomocysteine (SAH) is released (R = prenyl side chain). (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)

Fig. 24 in The scope of flavin-dependent reactions and processes in the model plant Arabidopsis thaliana

Fig. 24. Reaction catalyzed by COQ6 in ubiquinone biosynthesis. The FAD-dependent hydroxylation occurs in the 5-position of the aromatic ring as indicated (highlighted in red). COQ6 belongs to the class A FPMOs and depends on NAD(P)H as reductant. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)

Fig. 29 in The scope of flavin-dependent reactions and processes in the model plant Arabidopsis thaliana

Fig. 29. Reaction catalyzed by carotene cis-trans isomerase. The reaction shown requires reduced FAD for the redox-neutral cis-to-trans isomerization at position 9 and 9′ of prolycopene and generates the linear all-trans-lycopene. The reduced FAD is probably generated at the expense of NAD(P)H. Thus, the enzyme appears to possess a second activity that enables the transfer of a hydride from the reduced nicotinamide to the bound FAD cofactor.

Fig. 3 in 21-Hydroxypregnane 21-O-malonylation, a crucial step in cardenolide biosynthesis, can be achieved by substrate-promiscuous BAHD-type phenolic glucoside malonyltransferases from Arabidopsis thaliana and homolog proteins from Digitalis lanata

Fig. 3. Size exclusion chromatography (SEC) and indication of relative 21MaT activity investigation pools III (A) and IV (B) of the ammonium sulfate precipitation.

Fig. 4 in 21-Hydroxypregnane 21-O-malonylation, a crucial step in cardenolide biosynthesis, can be achieved by substrate-promiscuous BAHD-type phenolic glucoside malonyltransferases from Arabidopsis thaliana and homolog proteins from Digitalis lanata

Fig. 4. Docking of modeled AtPMaT1 (ribbon diagram) with an overlay of the potential pregnane substrates (Sub) (shown in grey). The catalytic histidine (His) and the cosubstrate (CoS) are also shown.

Fig. 1 in 21-Hydroxypregnane 21-O-malonylation, a crucial step in cardenolide biosynthesis, can be achieved by substrate-promiscuous BAHD-type phenolic glucoside malonyltransferases from Arabidopsis thaliana and homolog proteins from Digitalis lanata

Fig. 1. Postulated biosynthetic pathway of cardenolide formation in Digitalis. The malonylation step [8] is marked by a rectangle. 1 Putative side chain cleaving enzyme (SCCE), 2 NAD:3β-hydroxysteroid dehydrogenase (3βHSD), 3 Δ4,5-3-ketosteroid-isomerase (3KSI), 4 progesterone-5β-reductase (P5βR), 5 NAD:3β-hydroxysteroid dehydrogenase (3βHSD), 6 putative pregnane 14β-hydroxylase, 7 putative pregnane 21β-hydroxylase, 8 malonyl coenzyme A:21- hydroxypregnane 21-O-malonyltransferase (21MaT).

Fig. 6 in 21-Hydroxypregnane 21-O-malonylation, a crucial step in cardenolide biosynthesis, can be achieved by substrate-promiscuous BAHD-type phenolic glucoside malonyltransferases from Arabidopsis thaliana and homolog proteins from Digitalis lanata

Fig. 6. Docking of homology modeled malonyltransferases with 3-O-acetylketol (displayed in grey) showing the distances between the catalytic histidine (His), the hydroxy group to be malonylated (Sub) and the malonyl residue presented by the co-substrate (CoA). A AtPMaT1 B AtPMaT2 C DlMaT1.

Fig. 5 in 21-Hydroxypregnane 21-O-malonylation, a crucial step in cardenolide biosynthesis, can be achieved by substrate-promiscuous BAHD-type phenolic glucoside malonyltransferases from Arabidopsis thaliana and homolog proteins from Digitalis lanata

Fig. 5. Expression of Dlmat1, Dlmat2, Dlmat3, and Dlmat4 in different plant tissues measured by real-time quantitative PCR (qPCR). Expression rates are standardized to the values of the actin transcript in each tissue and were displayed in relation to the expression in young leaves (set to equal 1) for each Dlmat gene.