State reduction

Isoindolines comprise a group of well-characterized and easily synthesized substances, and being at the next stable reduction state below that of isoindoles, they constitute suitable precursors for synthesis of the latter. In principle, either oxidation or elimination from isoindolines should lead to isoindoles however, in view of the susceptibility of isoindoles to further oxidation, elimination has been preferred, and in all cases reported the leaving group has been placed on nitrogen rather than carbon. 

Oxidation-reduction titrations revealed the existence of two other oxidation-reduction states, EPR silent, designated as Ni-Si (Ni-Si-lent) and Ni-R (Ni-Reduced) (178, 180). A detailed study of the oxidation-reduction pattern involved enabled the following sequence of events (in the oxidation direction) to be written ... 

Demmig, B. Winter, K. (1988radiationless energy dissipation in intact leaves. In Ecology of Photosynthesis in Sun and Shade, ed. J.R. Evans, S. von Caemmerer and W.W. Adams III, pp. 151-62. Melbourne CSIRO. 

To sum up all three carbon sources provide amino acids, if the H2/C ratio is high enough (dependent on the oxidation and reduction state of carbon). Figure 4.3 shows the dependence of the amino acid yield on the reaction time. 

Throughout this book a major stress is on catalysis in organisms. Catalysis is confined to non-metals and metal ions of attacking power, either as Lewis acids or in oxidation/reduction and this excludes the simplest ions such as Na+, K+ and Ca2+ (and Cl- among anions). The transition metal ions and zinc are the most available powerful catalysts. The metals in a transition series are known to have selective binding properties, exchange rates and oxidation/reduction states, which can be put to use in catalysis in quite different ways (Table 2.13). It is noticeable that especially the complexes of metal elements... 

Criaud, A., C. Fouillac and B. Marty, 1989, Low enthalpy geothermal fluids from the Paris basin, 2 - oxidation-reduction state and consequences for the prediction of corrosion and sulfide scaling. Geothermics 18, 711-727. 

Recently there has been an increasing interest in self-oscillatory phenomena and also in formation of spatio-temporal structure, accompanied by the rapid development of theory concerning dynamics of such systems under nonlinear, nonequilibrium conditions. The discovery of model chemical reactions to produce self-oscillations and spatio-temporal structures has accelerated the studies on nonlinear dynamics in chemistry. The Belousov-Zhabotinskii(B-Z) reaction is the most famous among such types of oscillatory chemical reactions, and has been studied most frequently during the past couple of decades [1,2]. The B-Z reaction has attracted much interest from scientists with various discipline, because in this reaction, the rhythmic change between oxidation and reduction states can be easily observed in a test tube. As the reproducibility of the amplitude, period and some other experimental measures is rather high under a found condition, the mechanism of the B-Z reaction has been almost fully understood until now. The most important step in the induction of oscillations is the existence of auto-catalytic process in the reaction network. 

A. Sirijaruphan, A. Horvath, J. G. Goodwin, Jr and R. Oukaci, Cobalt aluminate formation in alumina-supported cobalt catalysts effects of cobalt reduction state and water vapor, Catal. Lett., 2003, 91, 89-94. 

Thiophene and thienothiophene units have been frequently used in thienoquinoid or condensed forms in the design of new molecular architecture (16). Incorporation of the thiophene or thienothiophene unit as a rc-bridge linker could stabilize the quinoidal structure in the reduced forms (Figures 13 and 14). These two-types of new dications (222+ and 232+) stabilize the presumed two-electron reduction state by contribution of the thienoquinoid substructures (22 and 23) instead of the quinoidal form in the dication 212+ (77). 

Vermilion, J.L. and Coon, M.J. (1978) Purified liver microsomal NADPH-cytochrome P-450 reductase. Spectral characterization of oxidation-reduction states. Journal of Biological Chemistry, 253 (8), 2694-2704. 

A. K. Srivastava and B. Volesky, Measurement and regulation of culture reduction state in Clostridium acetobutylicum, Biotechnol. Bioeng. 38, 181-190 (1991a). 

Surface fluorescence of NADH/NADPH can be recorded continuously with a DC fluorimeter and correlated with changes in experimental conditions. A mercury arc lamp (with a 340-375 nm filter in front) is used as a hght source for fluorescence excitation. The fluorescence response of reduced NADH/NADPH was measured at 450-510 nm. The DC fluorimeter and the Hg arc lamp are connected to the kidney by a trifurcated fiber optics light guide. NADH/NADPH fluorescence emission can be corrected for changes in tissue opacity by a 1 1 subtraction of reflectance changes at 340-375 nm from the fluorescence. To determine NADH/NADPH redox state of the total surface area of kidney cortex and to evaluate whether certain areas were insufficiently perfused, fluorescence photographs of the total surface area were taken. The study demonstrated that the surface fluorescence method is simple and provides specific information about the mitochondrial oxidation-reduction state. 

Mitochondrial oxidation-reduction state, NADH/NADPH SURFACE FLUORESCENCE IN LIVING TISSUES MITOGEN-ACTIVATED PROTEIN KINASE... 

The DesVll desosaminyl transferase naturally transfers D-desosamine to both 12- and 14-membered macrolactones, which is an example of inherent flexibility towards the acceptor aglycone. This unusual property of DesVll has been exploited to generate novel macrolide derivatives that differ in size of the macrolactone ring and in their oxygenation/reduction state. A Streptomyces lividans strain in which the genes involved in the biosynthesis and transfer of D-desosamine were... 

Many bacterial ferredoxins have two such clusters, each of which can be reduced to a paramagnetic state. In other proteins, 4Fe4S clusters can be oxidized to a paramagnetic state. The tetranuclear clusters in these two types of proteins are similar in structure, but they functionally shuttle between different reduction states. In both cases, each iron atom is additionally coordinated by four cysteinyl sulfur ligands. 

It is remarkable that the nitrogen cycle employs extreme oxidation-reduction states of nitrogen. Nitrification carries N from 3 to 5, whereas denitrification reduces N from 5+ to 0. A more direct cycle using only redox states of N between... 

On the other hand, Feigelson and his associates169,170,172-175 have reported that not only heme but also copper is an essential cofactor in both Pseudomonad and hepatic enzymes and that there are three different oxidation-reduction states of the enzyme, namely, a fully reduced form, E(Cu+, Fe2+) a half-reduced form, E(Cu+, Fe3+) or its valence isomer E(Cu2+, Fe2+) and a fully-oxidized form,... 

Many substances containing nitrogen have been shown to exist in intermediate reduction states corresponding to the semiquinone state, and for these substances it is found in general that the conditions are satisfied for resonance of the extended three-electron-bond type. The tetramethyl-p-phenylenediaminium ion, shown by its paramagnetism to be monomeric,68 resonates between the two structures of the type... 

Somewhat surprisingly, within the mitochondria the ratio [NAD+]/[NADH] is 100 times lower than in the cytoplasm. Even though mitochondria are the site of oxidation of NADH to NAD+, the intense catabolic activity occurring in the (3 oxidation pathway and the citric acid cycle ensure extremely rapid production of NADH. Furthermore, the reduction state of NAD is apparently buffered by the low potential of the (3-hydroxybutyrate-acetoacetate couple (Chapter 18, Section C,2). Mitochondrial pyridine nucleotides also appear to be at equilibrium with glutamate dehydrogenase.169... 

The Fe atoms of the cytochromes undergo oxidation and reduction during respiration, cycling between the ferrous (Fe2+) and ferric (Fe3+) oxidation states. The absorption spectra of the oxidized and reduced forms differ (fig. 14.4). In the 1930s, David Keilin used this property to measure the oxidation-reduction states of cytochromes in living cells. Under anaerobic conditions, the cytochromes rapidly became reduced in the presence of 02, they became oxidized. Certain molecules that inhibited respiration (CO, N3, or CN ) blocked the oxidation other inhibitors (amy-tal, rotenone, and malonate) blocked the reduction. Keilin found that the transfer of electrons from cytochrome c to 02... 

Fig. 4. Structure of molybdopterin and MoCo and its suggested attachment to plant NR apoenzyme. This model is adapted from Kramer et al. (1987) for the molybdopterin, Gardlik Rajagopalan (1990) for the pterin reduction state (shown here as a 5,6-dihydropterin, one of the three possible structures) and Neame Barber (1989) for the hypothetical thiol ligand from the side chain of Cysl80 of tobacco NR. A, Molybdopterin. B, MoCo.

Cyclic voltammetry proved to be a convenient method to reveal the oxido-reduction properties of the skin and of dermo-cosmetic creams. On the one hand, using microelectrodes, it was for the first time possible to evaluate the antioxidant properties on the skin surface. This simple protocol allowed to study in real time the global oxido-reductive state and to determine several antioxidant species. On the other hand, results showed the effect of oxidative stress on the evolution of the antioxidant properties of dermo-cosmetic products in time. 

Recycling Maine Waste Management Agency Office of Waste Recycling Reduction State House Station No. 154 Augusta, Maine 04333 Telephone 207-289-5300... 

The second proton transfer mechanism involves protonation of carboxyl or histidyl groups associated with electron carriers in the membrane and release of protons from these sites through proposed channels when the electron carrier is oxidized. This is essentially a proton channel system with movement through the channel gated by the oxidation-reduction state of the prosthetic group on the electron transport protein. The classical example of this is seen in cytochrome c oxidase (Figure 3). 

Kushnareva Y, Murphy AN, Andreyev A (2002) Complex i-mediated reactive oxygen species generation Modulation by cytochrome c and nad(p)(+) oxidation-reduction state. Biochem J 368 545-553... 

Answer As shown in Figure 19-6, the oxidation-reduction state of the carriers in the electron-transfer system varies with the conditions. 

NAD(P)H concentration in biomass and its ratio to NAD(P) gives a measure for the culture reduction status [35]. NAD(P)H can, in principle, be detected directly in vivo by in situ fluorescence measurement (see the chapter by Sonnleitner in this volume - the section on culture fluorescence). This measure serves as a biomass concentration sensor if the specific NAD(P)H concentration stays constant. If not, the ratio of culture fluorescence and biomass concentration, the specific fluorescence, can be a measure for the culture reduction state, or indicate other more complex events like metabolic pathway shifts [35] or even the formation of a variant in a culture [36] (see also Figs. 2 and 3). 

A combined application for culture energy charge and reduction state is the monitoring of events in Clostridium acetobutylicum at the shift from acid to solvent production [38] (Grupe and Gottschalk, 1992)... 

Fig. 2a-c. Growth of Bacillus stearothermophilus PV72 in continuous culture on a synthetic medium containing glucose (8 gH) as the sole carbon and energy source. The dissolved oxygen concentration was controlled at 50 % and the dilution rate was 0.3 h-1. As derived from the measured process variables, variant formation started at about 15-16 h after inoculation. Shown are the measures for a Respiration activity b External and internal reduction state (redox potential and culture fluorescence) c Cell density (Reprinted from J. Biotechnol. 54, K.C. Schuster et al., p. 19,1997, with permission from Elsevier Science)... 

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