Riboflavin phosphate mononucleotide

FMN is the standard biochemical abbreviation for flavin mononucleotide (or riboflavin phosphate). The sodium salt (95-97% pure) of FMN is used. This grade 1s inexpensive and is available from Sigma Chemical Company. Its purpose is to effect recycling of the catalytic amount used of the much more costly NAD. A larger than stoichiometric amount of FMN is employed in order to ensure rapid recycling of the NAO. 

The ribityl moiety is not linked to the isoalloxazine ring by a glycosidic linkage, and it is not strictly correct to caU FAD a dinucleotide. Nevertheless, this trivial name is accepted, as indeed is the even less correct term flavin mononucleotide for riboflavin phosphate. 

Other Coenzymes and Cofactors.— The chemical synthesis of riboflavin phosphates and their acetyl derivatives has been reinvestigated. Riboflavin 4 -monophosphate (10) is an important contaminant of commercial flavin mononucleotide (FMN), and... 

Flavin mononucleotide (FMN) (also called riboflavin phosphate)... 

TLC can be used to differentiate riboflavin from FMN (flavin mononucleotide) and some flavin analogs using various mobile phases riboflavin phosphates can be separated from riboflavin biphosphates, whereas the isomeric riboflavin phosphates co-migrate in all chromatographic systems studied (Nielsen et al., 1986). Bhushan and AH (1987) used TLC to analyze riboflavin in different matrices and also to separate and identify vitamin B2 from other water-soluble vitamins (Bi, Bj, and B12). Thielemann (1974) used TLC to separate and identify vitamin B2 from fat-soluble vitamins (A, Di, and E) in multivitamin preparations. 

Vitamin (riboflavin section 11.7) is important in a wide variety of oxidation and reduction reactions. A few enzymes contain riboflavin itself, while others contain a riboflavin derivative either riboflavin phosphate (sometimes called flavin mononucleotide) or flavin adenine dinucleotide (FAD Figure 2.14). When an enzyme contains riboflavin, it is usually covalently bound at the active site. Although riboflavin phosphate and FAD are not normally covalently bound to the enzyme, they are very tightly bound, and can be regarded as prosthetic groups. The resultant enzymes with attached riboflavin are collectively known as flavoproteins. 

Non- oxidative branch Pentose-5 -Phosphates Ribose-5-P 2 deoxy ribose-5-P 5 -phosphoribosyl-1 -pyrophosphate (PRPP) i) Structural components of nucleotides a. Basal structural component of RNA b. Basal structural component of DNA c. Precursor of both de novo and salvage synthesis of nucleotides ii) Intermediate products of purine metabolism and act as precursor molecules of cofactors, e g., riboflavin, flavin mononucleotide (FMN), flavin adenine di nucleotide (FAD) iii) Precursor of the amino acid. Histidine. 

Most flavoproteins, however, do not contain the mononucleotide, but rather flavin-adenine dinucleotide, abbreviated FAD. As in the pyridine nucleotides, adenosine monophosphate and riboflavin phosphate are joined by a pyrophosphate bond. The formula is shown below. 

Studies with these model systems have shown that the transport of riboflavin at low (e.g., micromolar) concentrations is temperature- and energy-dependent (it is inhibited by inhibitors of ATP production from energy substrates), it becomes saturated as the concentration of riboflavin increases, and it is sodium ion dependent. These characteristics are shared with many other types of small molecules that are actively transported across the gut wall. More specifically for riboflavin, the active transport mechanism involves phosphorylation (to riboflavin phosphate, also known as flavin mononucleotide, or FMN) followed by dephosphorylation, both occurring within the intestinal cells (Figure 1). This latter process is not shared by several other B vitamins, but it is one of a number of common strategies which the gut may use to entrap essential nutrients, and then relocate them, in a controlled manner and direction. A similar strategy is employed at other... 

Figure 2 Structure of riboflavin and its coenzyme derivatives. (A) Riboflavin (B) riboflavin phosphate (flavin mononucleotide, FMN) (C) flavin adenine dinucleotide (FAD).

Peptone and yeast extract were purchased from Kyokuto Pharmaceutical Co, Ltd. (Tokyo, Japan). Riboflavin and riboflavin phosphate (flavin mononucleotide, FMN) were obtained from Kanto Chemical Co., Inc. (Tokyo, Japan). Lecithin from egg was purchased from Wako Pure Chemical Co. (Osaka, Japan). Other reagents were commercially available analytical... 

Riboflavin-5 -Phosphate. Riboflavin-5 -phosphate [146-17-8] (vitamin B2 phosphate, flavin mononucleotide, FMN, cytoflav), C2yH22N402P,... 

The varions flavin phosphates and their acetyl derivatives were identified by pH titration, electrophoresis, and H-NMR, which permit direct analysis of crude reaction prodncts as well as rapid purity check of commercial flavin mononucleotide or riboflavin 5 -monophosphate (FMN or 5 -FMN) [7]. Riboflavin 4 -monophosphate was determined as the main by-product of commercial FMN by preparative TLC on cellulose with n-butanol/acetic add/water (5 2 3, v/v) as a solvent [7]. 

HPLC with fluorescence detection was employed for the analysis of riboflavin (RF), flavin mononucleotide (FMN) and flavin-adenin dinucleotide (FAD) in beer, wine and other beverages. The investigation was motivated by the finding that these compounds are responsible for the so-called taste of light which develops in beverages exposed to light. Samples were filtered and injected in to the analytical column without any other pretreatment. Separations were carried out in an ODS column (200 X 2.1mm i.d. particle size 5 pm). Solvents A and B were 0.05 M phosphate buffer (pH 3) and ACN, respectively. The... 

So what does riboflavin do As such riboflavin does nothing. Like thiamine, riboflavin must undergo metabolic change to become effective as a coenzyme. It fact, it undergoes two reactions. The first converts riboflavin to riboflavin-5-phosphate (commonly known as flavin adenine mononucleotide, FMN), about which we will say no more, and the second converts it to flavin adenine dinucleotide, FAD. The flavins are a class of redox agents of very general importance in biochemistry. FAD is the oxidized form and FADH2 is the reduced form. ... 

Riboflavin (vitamin B2) 6,7-dimethyl-9-(D-l-ribityl)isoalloxazine (63), was discovered as a coloring matter in milk in 1879, but its importance was not then realized. Deficiency causes lesions of the eye and of the angle of the mouth. Riboflavin is phosphorylated by adenosine triphosphate (ATP) to give riboflavin 5 -phosphate (flavinadenine mononucleotide, FMN) and then flavinadenine dinucleotide (FAD) (64 R = riboflavin). These function as prosthetic groups in a number of flavoproteins which are dehydrogenation catalysts by virtue of the oxidation-reduction properties of the isoalloxazine system. 

The metal complexes of riboflavin-5 -phosphate (flavin mononucleotide, FMN) have been studied. Zn(FMN)-2H20 shows some perturbation of the IR bands of the phosphate group, suggesting that metal binding occurs at the phosphate group.579 Reviews are available.9-15 468c h 1470... 

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

Flavin Mononucleotide, Sodium Salt Riboflavin 5 -Phosphate Ester Monosodium Salt Riboflavin 5 -Phosphate Ester Monosodium Salt, Dihydrate... 

Flavin mononucleotide (FMN)-adenosine and flavin adenine dinucleotide (FAD)-adenosine complexes show quenched triplet lifetimes compared to FMN alone, which is cited as evidence of intramolecular com-plexation between the flavins and adenosine by Shiga and Piette [142]. Adenosine phosphates also form complexes with FAD [143]. The com-plexation between a flavin and adenosine is identical to the intermolecular complexing of adenosine and flavin moieties, in the latter case enforced by hydrophobic bonding [144-146]. Rath and McCormick [147] have examined the riboflavin complexes of a series of purine ribose derivatives... 

In higher mammals, riboflavin is absorbed readily from the intestines and distributed to all tis.sues. It is the precursor in the biosynthesis of the cocnzyme.s flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD). The metabolic functions of this vitamin involve these Iwocoenzymes. which participate in numerous vital oxidation-reduction proces.ses. FMN (riboflavin 5 -phosphate) is produced from the vitamin and ATP by flavokinasc catalysis. This step con be inhibited by phcnothiazincs and the tricyclic antidepressants. FAD originates from an FMN and ATP reaction that involves reversible dinucicotide formation catalyzed by flavin nucleotide pyrophosphorylase. The.se coenzymes function in combination with several enzymes as coenzyme-en-zyme complexes, often characterized as, flavoproteins. 

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