Oxidoreductive

Sensitizers as well as desensitizers form a reversal oxidoreduction system with silver halides, according to both pH and pAg of the photographic emulsion. But besides the specific influence of the emulsion, the efficiency of a sensitizing dye depends on many other factors such as its adsorption, its spectral absorption, the energetic transfer yield, the dye aggregate to the silver halide, and finally on its desensitizing property in... 

Ortho esters, in synthesis of symmetrical trimethine thiazolocyanines, 54 Oxazolone, for neutrocyanines, 27 Oxidation potentials, of dyes, 75 of mesosubstituted dyes, in relation with absorption, 77 of polymethine dyes, 72 Oxidoreduction, relation between sensitizers, and silver halides, 78 4-Oxo-disubstituted 2-aminoselenazoles, table of products, 262 Oxonols, nomenclature of, 26 in synthesis of dimethine neutrocyanines, 62... 

Figure 11-2. Oxidoreduction of isoalloxazine ring in fiavin nucieotides via a semi-quinone (free radicai) intermediate (center).

An additional component is the iron-sulfur protein (FeS nonheme iron) (Figure 12-6). It is associated with the flavoproteins (metallofiavoproteins) and with cytochrome b. The sulfur and iron are thought to take part in the oxidoreduction mechanism between flavin and Q, which involves only a single e change, the iron atom undergoing oxidoreduction between Fe " and Fe k... 

Flavin Coenzymes Are Electron Carriers in Oxidoreduction Reactions... 

GSHPx, CAT and SOD, which normally protect cells from free-radical damage have not been detected in aqueous humour. It has therefore been su ested that damage by free radicals and hydrogen peroxide to the anterior segment is prevented by a non-enzymatic extracellular oxidoreduction system involving a constant supply of reduced glutathione to the aqueous fluid from the ciliary epithelium, cornea and lens (Riley, 1983). 

Husain, M. and Husain, Q. (2008) Applications of redox mediators in the treatment of organic pollutants by using oxidoreductive enzymes a review. Critical Reviews in Environmental Science and Technology, 38, 1-42. 

Proteinoids also have other properties, such as the formation of cell-like structures (microspheres), and they show weak or very weak activities such as decarboxylation (Rohlfing, 1967) or oxidoreduction (Dose and Zaki, 1971). 

Dec J, Bollag JM (1990) Detoxification of substituted phenols by oxidoreductive enzymes through polymerization reactions. Arch Environ Contam Toxicol 19 543-550... 

Husain Q (2006) Potential applications of the oxidoreductive enzymes in the decolorization and detoxification of textile and other synthetic dyes from polluted water a review. Crit Rev Biotechnol 26 201-221... 

Oxidoreduction driven Methyl transfer driven Light absorption driven... 

Hoch U, ScheUer G, Schmitt M, Schreier P, Adam W, Saha-MoUer CR (1995) Enzymes in synthetic organic chemistry selective oxidoreductions catalyzed by the metaUoenzymes lipoxygenase and peroxidase. In Werner H, Simdermeyer J (eds) Stereoselective reactions of metal-activated molecules, 2nd Symposium. Vieweg, Braimschweig, p 33 Adam W, Korb MN (1997) Tetrahedron Asymmetry 8 1131... 

Hydrogenase Otho H2o para H2 conversion, cytochrome c3 oxidoreduction Yagi et al., 1969 [1] Kimura et al.,1979 [2]... 

Lactate and pyruvate are interconverted within the cytoplasm, depending upon the NADiNADH ratio. In the cytoplasm, the ratio of lactate to pyruvate reflects the oxidoreduction state. 

The synthesis of adrenal steroids is illustrated in Fig. 5.3.1. Cortisol, corticosterone, and aldosterone are formed by sequential hydroxylations and oxidoreductions from pregnenolone and progesterone. 17a-Hydroxypregnenolone (17HP) is a branchpoint constituent because it can be converted to cortisol or adrenal androgens. All of the components of this pathway can be quantified by MS/MS. The steroids around the periphery are urinary metabolites and these are measured by GC-MS following hydrolysis of conjugates and derivatization. 

While defective 11/1HSD I seemed the most likely cause of the disorder, no loss-of-function mutations were found in 1 IjSHSD I in the first patients investigated [61 ]. The cause of the disorder in these cases proved to be mutations in hexose-6-phos-phate dehydrogenase (H6PDH), the enzyme that supplies electrons to the NADPH utilized in oxidoreduction [15]. Later studies have found 11/311814 I mutations in some affected individuals. Thus, there are two monogenic disorders giving rise to a similar phenotype cortisone reductase deficiency caused by lljSHSD I mutations,... 

In the case of two flavoenzyme oxidase systems (glucose oxidase (18) and thiamine oxidase s where both oxidation-reduction potential and semiquinone quantitation values are available, semiquinone formation is viewed to be kinetically rather than thermodynamically stabilized. The respective one-electron redox couples (PFl/PFl- and PFI7PFIH2) are similar in value (from essential equality to a 50 mV differential) which would predict only very low levels of semiquinone (32% when both couples are identical) at equilibrium. However, near quantitative yields (90%) of semiquinone are observed either by photochemical reduction or by titration with dithionite which demonstrates a kinetic barrier for the reduction of the semiquinone to the hydroquinone form. The addition of a low potential one-electron oxidoreductant such as methyl viologen generally acts to circumvent this kinetic barrier and facilitate the rapid reduction of the semiquinone to the hydroquinone form. 

Although far from exhaustive, Table 3 shows that tetracoordinated compounds as diverse as phosphonium salts, phosphinates, thiophosphinates, phosphine oxides, phos-phonium ylides and halophosphates can ail lead to P(V) derivatives by addition, substitution, or oxidoreduction reactions. 

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