The formation constants of the species formed in the systems H+ + Mo(VI) + histidine and H+ +histidine have been determined at different aqueous solutions of methanol (0 - 45 % v/v) at 25 °C andconstant ionic strength (0.1 mol dm-3 sodium perchlorate), using a combination of spectrophotometricand potentiometric techniques. The composition of the complex species was determined by thecontinuous v...

I . The oral administration of sodium molybdate caused a rapid rise of molybdenum in the milk of cows and goats fed on a low-molybdenum diet, but did not affect the xanthine oxidase activities of the milk of either species. 2. In the milks of cows not dosed with sodium molybdate, the regression of the xanthine oxidase activity ( y ) on the molybdenum content (x) was found to be (r = +0.9386; P ...

The changes in optical and EPR spectra observed during the anaerobic titration of xanthine oxidase with dithionite can be accounted for by simple oxidation-reduction equilibria involving Mo(VI) u MO(V) H Mo(IV); FAD cf FADH. ++ FADH2, and the l-electron reduction of each of the two ironsulfur centers. The equilibrium constants so obtained permit the calculation of the relative probabilities of ...

Absorption and EPR spectroscopic properties of purified dimethyl sulfoxide (Me2SO) reductase from Rhodobacter sphaeroides f. sp. denitrificans have been examined. The absence of prosthetic groups other than the molybdenum center in the enzyme has made it possible to study its absorption properties. The enzyme displays multiple absorbance peaks in both the oxidized and the dithionite-reduced for...

1. The mid-point reduction potentials of the various groups in xanthine oxidase from bovine milk were determined by potentiometric titration with dithionite in the presence of dye mediators, removing samples for quantification of the reduced species by e.p.r. (electron-paramagnetic-resonance) spectroscopy. The values obtained for the functional enzyme in pyrophosphate buffer, pH8.2, are: Fe/S c...

Colorless alkylmolybdates(VI) of composition R-M0O3are generated in aqueous solutions by the alkaline hydrolysis of complexes R-Mo(Bpy)(0)aBr (Bpy = 2,2'-bipyridyl, R = CH3 and higher alkyl). At room temperature in alkaline aqueous solution, the new organometallic derivatives of oxomolybdate(VI) are remarkably resistant against Mo-C bond hydrolysis. Decomposition occurs more rapidly on heating,...

Resonance Raman spectroscopy has been used to define active site structures for oxidized Mo(VI) and reduced Mo(IV) forms of recombinant Rhodobacter sphaeroides biotin sulfoxide reductase expressed in Escherichia coli. On the basis of (18)O/(16)O labeling studies involving water and the alternative substrate dimethyl sulfoxide and the close correspondence to the resonance Raman spectra previousl...

The oxo-diperoxo molybdenum(VI) complex MoO(O(2))(2).2QOH (QOH = 8-quinilinol) was prepared and characterized by elemental analysis, IR and UV-Vis spectra. The ionic liquids (ILs) [bmim][BF(4)], [hydemim][BF(4)], and [bmim][PF(6)] were characterized by (1)H-NMR and UV-Vis spectra. The epoxidation of a technical mixture of methyl oleate and methyl linoleate with H(2)O(2), in [bmim][BF(4)], [hyde...