Flavin mononucleotide FMN

The first structure, flavodoxin (Figure 4.14a), has one such position, between strands 1 and 3. The connection from strand 1 goes to the right and that from strand 3 to the left. In the schematic diagram in Figure 4.14a we can see that the corresponding a helices are on opposite sides of the p sheet. The loops from these two p strands, 1 and 3, to their respective a helices form the major part of the binding cleft for the coenzyme FMN (flavin mononucleotide). 

All NOS isoforms utilize L-arginine as the substrate, and molecular oxygen and reduced nicotinamide adenine dinucleotide phosphate (NADPH) as cosubstrates. Flavin adenine dinucleotide (FMN), flavin mononucleotide (FAD), and (6R)-5,6,7,8-tetrahydro-L-biopterin (BH4) are cofactors of the enzyme. All NOS isoforms contain heme and bind calmodulin. In nNOS and eNOS,... 

FIGURE 32-7 Sources of free radical formation which may contribute to injury during ischemia-reperfusion. Nitric oxide synthase, the mitochondrial electron-transport chain and metabolism of arachidonic acid are among the likely contributors. CaM, calcium/calmodulin FAD, flavin adenine dinucleotide FMN, flavin mononucleotide HtT, tetrahydrobiopterin HETES, hydroxyeicosatetraenoic acids L, lipid alkoxyl radical LOO, lipid peroxyl radical NO, nitric oxide 0 "2, superoxide radical. 

The principles of ESR spectroscopy are very similar to NMR spectroscopy but the technique gives information about electron delocalizations rather than molecular structure and it enables the study of electron transfer reactions and the formation of paramagnetic intermediates in such reactions. In some situations, information regarding molecular structure can be obtained when suitable prosthetic groups are part of a molecule, e.g. FMN (flavin mononucleotide) in certain enzymes or the haem group in haemoglobin. Sometimes it is possible to attach suitable groups to molecules to enable their reactions to be monitored by ESR techniques. Such spin labels as they are called, are usually nitroxide radicals of the type... 

The oxidation state of thiazolines and oxazolines can be adjusted by additional tailoring enzymes. For instance, oxidation domains (Ox) composed of approximately 250 amino acids utilize the cofactor FMN (flavin mononucleotide) to form aromatic oxazoles and thiazoles from oxazolines and thiazolines, respectively. Such domains are likely utilized in the biosynthesis of the disorazoles, " diazonimides, bleomycin, and epothiolone. The typical domain organization for a synthetase containing an oxidation domain is Cy-A-PCP-Ox however, in myxothiazol biosynthesis one oxidation domain is incorporated into an A domain. Alternatively, NRPSs can utilize NAD(P)H reductase domains to convert thiazolines and oxazolines into thiazolidines and oxazolidines, respectively. For instance, PchC is a reductase domain from the pyochelin biosynthetic pathway that acts in trans to reduce a thiazolyinyl-Y-PCP-bound intermediate to the corresponding thiazolidynyl-Y-PCP. ... 

FMN, flavin mononucleotide, is simply the flavin-containing stracture from the dinucleotide FAD. 

Figure 3 Schematic representation of nitric oxide synthase isoforms and cytochrome P450 reductase. Haem, heme PDZ, PDZ domain (GLGF repeats) CaM, calmodulin FMN, flavin mononucleotide FAD, flavin adenine dinucleotide (adapted from Hobbs et al., 1999).

Flavin adenine diphosphate (FAD, flavin adenine dinucleotide) and riboflavin 5 -monophosphate (FMN, flavin mononucleotide), whose structures are shown in Fig. 15-7, are perhaps the most versatile of all... 

ADP adenosine-5 -diphosphate FMN flavin mononucleotide (oxidized form)... 

Note e represents the number of electrons that are transferred. aKrebs cycle. Complexes of the oxidative phosphorylation, Abbreviations FAD, flavine adenine diphosphonucleotide FMN, flavine mononucleotide GSFH, glutathione ... 

FMN Flavin mononucleotide as sodium salt Riboflavine 5 -(dihydrogen phosphate), monosodium salt (8,9) (130-40-5)... 

The whole thing is FAD. Cutting FAD in half down the middle of the pyrophosphate link would give us two nucleotides, AMP and FMN (flavin mononucleotide). The sugar in each case is ribose (in its furanose form in AMP but in open-chain form in FMN) so the flavin nucleoside is riboflavin. We can abbreviate this complex structure to the reactive part, which is the flavin. The rest we shall just call R ... 

Figure 16-8. Structure and labeling of the isoalloxazine ring and related flavins. Isoalloxazine (benzo[g]pteridine-2,4(3H,10H)-dione) R = R = H. FMN (Flavin mononucleotide) R = CH3 R = CH2- (CH0H)3-CH20-P0f-...

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