2140-48-9Relevant articles and documents
Reduction of flavodoxin by electron bifurcation and sodium Ion-dependent reoxidation by NAD+ catalyzed by ferredoxin-NAD+ reductase (Rnf)?
Chowdhury, Nilanjan Pal,Klomann, Katharina,Seubert, Andreas,Buckel, Wolfgang
, p. 11993 - 12002 (2016)
Electron-transferring flavoprotein (Etf) and butyryl-CoA dehydrogenase (Bcd) from Acidaminococcus fermentans catalyze the endergonic reduction of ferredoxin by NADH, which is also driven by the concomitant reduction of crotonyl-CoA by NADH, a process called electron bifurcation. Here we show that recombinant flavodoxin from A. fermentans produced in Escherichia coli can replace ferredoxin with almost equal efficiency. After complete reduction of the yellow quinone to the blue semiquinone, a second 1.4 times faster electron transfer affords the colorless hydroquinone. Mediated by a hydrogenase, protons reoxidize the fully reduced flavodoxin or ferredoxin to the semi-reduced species. In this hydrogen-generating system, both electron carriers act catalytically with apparent Km = 0.26 μM ferredoxin or 0.42 μM flavodoxin. Membrane preparations of A. fermentans contain a highly active ferredoxin/flavodoxin-NAD+ reductase (Rnf) that catalyzes the irreversible reduction of flavodoxin by NADH to the blue semiquinone. Using flavodoxin hydroquinone or reduced ferredoxin obtained by electron bifurcation, Rnf can be measured in the forward direction, whereby one NADH is recycled, resulting in the simple equation: crotonyl-CoA + NADH+ H + = butyryl-CoA + NAD+ with Km= 1.4 μM ferredoxin or 2.0 μM flavodoxin. This reaction requires Na + (Km= 0.12 mM)orLi + (Km = 0.25 mM) for activity, indicating that Rnf acts as a Na + pump. The redox potential of the quinone/semiquinone couple of flavodoxin (Fld) is much higher than that of the semiquinone/hydroquinone couple. With free riboflavin, the opposite is the case. Based on this behavior, we refine our previous mechanism of electron bifurcation.
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Peng
, p. 42,46 (1956)
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Talbert,Huennekens
, p. 4671,4673 (1956)
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Identification of an α-Oxoamine Synthase and a One-Pot Two-Step Enzymatic Synthesis of α-Amino Ketones
Zhou, Ting,Gao, Du,Li, Jia-Xin,Xu, Min-Juan,Xu, Jun
supporting information, p. 37 - 41 (2020/12/21)
Alb29, an α-oxoamine synthase involved in albogrisin biosynthesis in Streptomyces albogriseolus MGR072, was characterized and responsible for the incorporation of l-glutamate to acyl-coenzyme A substrates. Combined with Alb29 and Mgr36 (an acyl-coenzyme A ligase), a one-pot enzymatic system was established to synthesize seven α-amino ketones. When these α-amino ketones were fed into the alb29 knockout strain Δalb29, respectively, the albogrisin analogs with different side chains were observed.
ATP Regeneration System in Chemoenzymatic Amide Bond Formation with Thermophilic CoA Ligase
Lelièvre, Chloé M.,Balandras, Mélanie,Petit, Jean-Louis,Vergne-Vaxelaire, Carine,Zaparucha, Anne
, p. 1184 - 1189 (2020/01/22)
CoA ligases are enzymes catalyzing the ATP-dependent addition of coenzyme A to carboxylic acids in two steps through an adenylate intermediate. This intermediate can be diverted by a nucleophilic non enzymatic addition of amine to get the corresponding amide for synthetic purposes. To this end, we selected thermophilic CoA ligases to study the conversion of various carboxylic acids into their amide counterparts. To limit the use of ATP, we implemented an ATP regeneration system combining polyphosphate kinase 2 (PPK2 Class III) and inorganic pyrophosphatase. Suitability of this system was illustrated by the lab-scale chemoenzymatic synthesis of N-methylbutyrylamide in 77 % yield using low enzyme loading and 5 % molar ATP.