Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Extraction flavins

Figure 7 HPLC chromatogram of phenol-extracted flavins from pooled cow s milk. (A) 7a-hydroxyriboflavin (B) 8a-hydroxyriboflavin (C) FAD (D) riboflavin (E) 10-(2 -hydroxyethyl)flavin. (From Ref. 26.)... [Pg.421]

If the luciferase sample solution contains a flavin-reductase, luciferase activity can be measured by the addition of FMN and NADH, instead of FMNH2. In this case, the turnover of luciferase takes place repeatedly using the FMNH2 that is enzymatically generated thus, the luminescence reaction continues until aldehyde or NADH is exhausted. A crude luciferase extracted from luminous bacteria usually contains a flavin-reductase. [Pg.40]

No information is available on the chemical nature of the luminophore, although the photoprotein must contain a chro-mophore to emit luminescence and fluorescence. Acid treatment of the protein, followed by extraction with organic solvents, did not yield coelenteramide or coelenteramine, indicating that this luminescence system is unrelated to coelenterazine. A flavin (FAD) was found in partially purified preparations of photoprotein, but not in highly purified preparations. [Pg.225]

Various TLC solvent systems were used to eonfirm the presenee of flavins in plain yogurt and raw egg white (or egg powder) [5], The mean content of flavin compounds (Figure 10.1) have been analyzed in plain yogurts and bioyogurts [6]. Concentrated flavin extracts were passed through a column packed with resoreinol-type resin R-15... [Pg.238]

The thermophilic enzyme DszD from Paenibacillus All-2 has been cloned into E. coli and characterized [172], The sequence of this enzyme showed 30% similarity to the major flavin reductase of Vibrio fischeri. The optimum activity was reported to be at 45°C in resting cell cultures and 55°C in cell-free extracts. [Pg.100]

Based on the previous publications, azo dye can be reduced by azoreductase-catalyzed reduction under anaerobic conditions. But still there is a speculation whether bacterial flavin reductases are responsible for the azo reductase activity observed with bacterial cell extracts. In a published report, it is reported that flavin reductases are indeed able to act as azo reductases [24]. Bacteria produce extracellular oxidative enzymes, which are relatively nonspecific enzymes catalyzing the oxidation of a variety of dyes. It was reported that so many diverse groups of bacteria play a role in decolorization. It has been also reported that mixed microbial community could reduce various azo dyes, and members of the y-proteabacteria and sulfate reducing bacteria (SRB) were found to be prominent members of mixed bacterial population by using molecular methods to determine the microbial population dynamics [1],... [Pg.63]

To reach the reductive step of the azo bond cleavage, due to the reaction between reduced electron carriers (flavins or hydroquinones) and azo dyes, either the reduced electron carrier or the azo compound should pass the cell plasma membrane barrier. Highly polar azo dyes, such as sulfonated compounds, cannot pass the plasma membrane barrier, as sulfonic acid substitution of the azo dye structure apparently blocks effective dye permeation [28], The removal of the block to the dye permeation by treatment with toluene of Bacillus cereus cells induced a significant increase of the uptake of sulfonated azo dyes and of their reduction rate [29]. Moreover, cell extracts usually show to be more active in anaerobic reduction of azo dyes than whole cells. Therefore, intracellular reductases activities are not the best way to reach sulfonated azo dyes reduction the biological systems in which the transport of redox mediators or of azo dye through the plasma membrane is not required are preferable to achieve their degradation [13]. [Pg.200]

A method has been reported [481] for the determination of flavins in seawater. The method is based on solid-phase extraction. With ion-pair HPLC using fluorescence detection, concentrations in the picomolar range can be measured. [Pg.440]

Babior, who has studied this enzyme at several stages of its purification, found in lysates of PMNs which were activated with zymosan that of eight potential biological reductants only reduced pyridine nucleotides supported the formation of O ". The K , for NADPH was less than the K , for NADH and the activity was decreased in preparations from three patients with chronic granulomatous disease. In accord with predictions based on reaction 7, 0.55 molecule of O7 was measured per molecule of NADPH oxidized under conditions of saturating concentrations of cytochrome c The enzyme which was extracted with Triton X-100 from a granule-rich fraction from activated PMNs, required an external source of FAD for the formation of O from NADPH . Riboflavin and FMN would not substitute. Flavin adenine dinucleotide was proposed as a necessary cofactor, which was probably lost when the enzyme was treated with the detergent. [Pg.51]

The phenolics ( + )catechin and (— )epicatechin are common flavanols in several fruits (128). Apples and pears contain other phenolic compounds such as quinic, shikimic, chlorogenic, and caffeic acids (39). Durkee and Poapst (162) reported that the two major phenolic constituents of core tissues and seeds of McIntosh apples were chlorogenic acid and phloridzin. After hydrolysis of extracts from core tissues, the identified phenolics were phloretin, caffeic acid, p-coumaric acid, phloretic acid, and trace amounts of ferulic acid. Studies have shown that apple leucoanthocyanins yield catechin, epicatechin, cyanidin, and pelargonidin after hydrolysis (163, 164). Van Buren et al. (164) also reported that a purified leucoanthocyanin from apples was either a dimer or oligomer containing ( —) epicatechin, and 5,7,3, 4 -flavin-3,4-diol. [Pg.37]

LF Russell, JT Vanderslice. Non-degradative extraction and simultaneous quantitation of riboflavin, flavin mononucleotide, and flavin adenine dinucleotide in foods by HPLC. Food Chem 43 151-162, 1992. [Pg.472]

One possibility is to use low molecular weight mediators, which can shuttle electrons between the (GO)red and the surface of the electrode, thus bypassing the reaction with oxygen (see Fig. 7.9, Scheme 2). The obvious prerequisite for this scheme is the mobility of the mediator Mox, which must penetrate into the interior of the enzyme extract the electrons from the two flavin redox centers located deep inside the GO molecule (Fig. 7.15) and transport them to the electrode. [Pg.227]

Tissue also contains some endogenous species that exhibit fluorescence, such as aromatic amino acids present in proteins (phenylalanine, tyrosine, and tryptophan), pyridine nucleotide enzyme cofactors (e.g., oxidized nicotinamide adenine dinucleotide, NADH pyridoxal phosphate flavin adenine dinucleotide, FAD), and cross-links between the collagen and the elastin in extracellular matrix.100 These typically possess excitation maxima in the ultraviolet, short natural lifetimes, and low quantum yields (see Table 10.1 for examples), but their characteristics strongly depend on whether they are bound to proteins. Excitation of these molecules would elicit background emission that would contaminate the emission due to implanted sensors, resulting in baseline offsets or even major spectral shifts in extreme cases therefore, it is necessary to carefully select fluorophores for implants. It is also noteworthy that the lifetimes are fairly short, such that use of longer lifetime emitters in sensors would allow lifetime-resolved measurements to extract sensor emission from overriding tissue fluorescence. [Pg.299]

NADPH-cytochrome P-460 reductase is composed of a single polypeptide chain of 70,000-80,000 molecular weight 369, 371, 373, 374) associated with one molecule of FAD and one molecule of FMN 370, 371, 373, 378, 379). These results apply to the enzyme whether solubilized by proteolytic digestion or by detergent extraction. The minimum molecular weight based on the flavin content is somewhat higher, 87,000 (373), possibly indicative of the flavin lability observed upon irradiation in ammonium sulfate 380). The detergent-solubilized reductase has a lower flavin content, 0.64 and 0.79 moles of FMN and FAD per 79,000 g of enzyme 371). The absorbance ratio, 275 nm 455 nm of 6.5, indicates a relatively low content of aromatic amino acids 373, 374) The extinction of the flavins at 455 nm is 10.7 mM cm" (373). [Pg.166]

The dehydrogenase preparations obtained by acid-ethanol extraction of particles at elevated temperatures vary considerably in their content of flavin, iron, and labile sulfide, and in their activities. These differences appear to be largely a consequence of destruction of the iron-sulfur chromophore at acid pH. As seen in Fig. 10, incubation of the low molecular weight dehydrogenase preparation of Hatefl and Stempel at pH 4.8 and 38° resulted after 1 hr in nearly complete loss of labile sulfide (Fig. IOC) and reductase activity with respect to menadione, cytochrome c. [Pg.194]

Kumar et al. (63) have estimated the molecular weight of the acid-ethanol-extracted dehydrogenase by Sephadex gel exclusion to be approximately 70,000. Assuming one mole of FMN per mole of enzyme, the molecular weight of 70,000 agrees with the flavin content of the preparations of Kumar et al. (63), Pharo et al. (64), and Hatefi and Stempel... [Pg.195]


See other pages where Extraction flavins is mentioned: [Pg.187]    [Pg.188]    [Pg.187]    [Pg.188]    [Pg.187]    [Pg.188]    [Pg.187]    [Pg.188]    [Pg.195]    [Pg.11]    [Pg.639]    [Pg.140]    [Pg.100]    [Pg.314]    [Pg.188]    [Pg.30]    [Pg.26]    [Pg.104]    [Pg.10]    [Pg.162]    [Pg.165]    [Pg.4]    [Pg.101]    [Pg.266]    [Pg.190]    [Pg.190]    [Pg.638]    [Pg.337]    [Pg.344]    [Pg.435]    [Pg.80]    [Pg.80]    [Pg.391]    [Pg.174]    [Pg.179]    [Pg.191]    [Pg.217]   
See also in sourсe #XX -- [ Pg.279 ]




SEARCH



Flavines

Flavins

© 2024 chempedia.info