FMN-reductase

Fig. 2.1 Mechanism of the bacterial bioluminescence reaction. The molecule of FMNH2 is deprotonated at N1 when bound to a luciferase molecule, which is then readily peroxidized at C4a to form Intermediate A. Intermediate A reacts with a fatty aldehyde (such as dodecanal and tetradecanal) to form Intermediate B. Intermediate B decomposes and yields the excited state of 4a-hydroxyflavin (Intermediate C) and a fatty acid. Light (Amax 490 nm) is emitted when the excited state of C falls to the ground state. The ground state C decomposes into FMN plus H2O. All the intermediates (A, B, and C) are luciferase-bound forms. The FMN formed can be reduced to FMNH2 in the presence of FMN reductase and NADH.

In the living cells of luminous bacteria, FMNH2 is produced by the reduction of FMN with NADH catalyzed by FMN-reductase. This process is, in effect, the recycling of FMN. In the cells, a long-chain aldehyde is produced by the reduction of the corresponding long-chain acid, which is also a recycling process. 

The discovery that the rate of reaction of the desulfurization of fossil fuels is enhanced by the addition of a flavoprotein to the biocatalyst was then claimed in the other two family patents. So, the patents are related to the use of a flavoprotein, particularly FMN reductase, in addition to the biocatalytic material for increasing the rate of desulfurization. In the World patent, ten more claims were allowed, compared to the US issued patent. The excess claims include a set of dependant claims in which the microorganism containing the recombinant DNA molecule is considered. However, in the invention a two-step process is stated, it is just the contact between the fossil fuel with an aqueous phase containing a biocatalyst and a rate-enhancing amount of a flavoprotein. There is no indication whatsoever on how much that amount could be. 

Gerlo E., Charlier J., Identification of NADH-specific and NADPH-specific FMN reductase in Beneckea harveyi, Eur. J. Biochem. 1975 57 461-467. 

A more efficient system which allows the use of catalytic amounts of nicotineamide adenine dinucleotide and flavin adenine mononucleotide and allows the reaction to be efficiently scaled up, utilizes a catalytic recycling system. Flavin adenine mononucleotide (FMN) reductase (E.C. 1.6.8.1) is used to catalyze the oxidation of reduced nicotineamide adenine dinucleotide by FMN under formation of reduced flavin adenine mononucleotide which in turn is oxidized in both versions to flavin adenine mononucleotide by oxygen169. 

Vorontsov, 1.1., Minasov, G., Brunzelle, J.S., Shuvalova, L., Kir-yukhina, O., Collart, F.R., Anderson, W.F. (2007). Crystal stmcture of an apo form of Shigella flexneri ArsH protein with an NADPH-dependent FMN reductase activity. Protein Sci. 16 2483-90. 

Other NAD4 regeneration approaches are based on the transfer of hydride either to PQQ (catalyzed by diaphorase)1331, directly to flavins155-571, or to flavins via FMN reductase catalysis[581. Direct hydride transfer to flavins has the advantage that the alloxazine acceptor can be chosen freely, e. g. cheap riboflavin instead of FAD. On the... 

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