Reduction molybdate-catalyzed

An analogous glucose sensor has been developed by Umana and Waller (1986). Glucose measurement was carried out by reduction of iodine formed from iodide in a molybdate-catalyzed reaction. The current did not reach a stationary value but increased linearly with time. Obviously the main part of glucose oxidation was catalyzed by GOD leached out into the measuring solution. Therefore the sensitivity dropped to 25% of the initial value after 5 measurements and after 10 days the enzyme was completely exhausted. 

Where water softening is provided and there is no reduction in system water TDS, treatments are primarily based on inorganic corrosion inhibitor blends (nitrite, molybdate, etc.). Under these circumstances, there is no benefit in using an expensive organic oxygen scavenger to keep the TDS level low, and a common chemical such as catalyzed sodium sulfite may be used. 

Reduction with carbon monoxide at high temperatures can form either carbonyl sulfide or sulfur depending on the catalyst used. With cobalt molybdate, COS is the primary product. On the other hand, lanthanum titanate catalyzes the reaction to form sulfur. 

Mechanisms proposed for reactions envisage complex reaction pathways. Thus in the oxidation of methacrolein catalyzed by H3PM012O40, the chemisorption of the aldehyde precedes the redox step and is thought to occur through the acid-promoted formation of a gem-diol molybdate ester. The subsequent oxidation to methacrylic acid involves Mo(VI) undergoing reduction to Mo(V). Molecular oxygen only serves to reoxidize the reduced polyanion. 

A 25 nm-thick layer with a Ni/Mo atomic ratio of 4 1 was indeed detected by AES and EDS. The mixed Ni-Mo oxide is claimed to catalyze the HER. Next, when the polarization is increased, the mixed oxide is further reduced to a surface compound that inhibits the HER and is more catalytic for reduction of molybdate and nickel ions, fonning an alloy according to the reaction ... 

Bakker et al. [25] replaced the zinc in thermolysin with anions snch as molybdate, selenate, or tungstate to give an enzyme that catalyzed the nonenantioselective oxidation of thioanisoles with hydrogen peroxide. Van de Velde et al. [26] added a vanadate ion to the active site of phytase to create a catalyst for enantioselective oxididation of thioanisole to the sulfoxide in 66% ee. Selenosubtihsin (protease subtilisin where a selenoserine replaces the active-site serine) catalyzes the enantioselective reduction of hydroperoxides [27] with enantioselectivity >100 for one substrate. 

Hagedoorn et al. have investigated the redox properties of tungsten-substituted DMSO reductase from R. capsulatus The enzyme is produced by growing R. capsulatus cells on tungstate rather than molybdate and structural and spectroscopic studies have shown that the W-enzyme exhibits similar features to its native Mo analogue. An EPR redox titration concentration of the W state determined and redox potentials of -194 mV and -134 mV vs. NHE, respectively, at pH 7.0, which are considerably lower than the values reported for the Mo-containing R. sphaeroides DMSO reductase. These redox potentials are consistent with the known ability of (Mo) DMSO reductase to catalyze both the reduction of DMSO and the oxidation of DMS. 

---