1,259 research outputs found

    Steady-state kinetics of the tungsten containing aldehyde: Ferredoxin oxidoreductases from the hyperthermophilic archaeon Pyrococcus furiosus

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    The tungsten containing Aldehyde:ferredoxin oxidoreductases (AOR) offer interesting opportunities for biocatalytic approaches towards aldehyde oxidation and carboxylic acid reduction. The hyperthermophilic archaeon Pyrococcus furiosus encodes five different AOR family members: glyceraldehyde-3-phosphate oxidoreductase (GAPOR), aldehyde oxidoreductase (AOR), and formaldehyde oxidoreductase (FOR), WOR4 and WOR5. GAPOR functions as a glycolytic enzyme and is highly specific for the substrate glyceraldehyde-3-phosphate (GAP). AOR, FOR and WOR5 have a broad substrate spectrum, and for WOR4 no substrate has been identified to date. As ambiguous kinetic parameters have been reported for different AOR family enzymes the steady state kinetics under different physiologically relevant conditions was explored. The GAPOR substrate GAP was found to degrade at 60 °C by non-enzymatic elimination of the phosphate group to methylglyoxal with a half-life t1/2 = 6.5 min. Methylglyoxal is not a substrate or inhibitor of GAPOR. D-GAP was identified as the only substrate oxidized by GAPOR, and the kinetics of the enzyme was unaffected by the presence of L-GAP, which makes GAPOR the first enantioselective enzyme of the AOR family. The steady-state kinetics of GAPOR showed partial substrate inhibition, which assumes the GAP inhibited form of the enzyme retains some activity. This inhibition was found to be alleviated completely by a 1 M NaCl resulting in increased enzyme activity at high substrate concentrations. GAPOR activity was strongly pH dependent, with the optimum at pH 9. At pH 9, the substrate is a divalent anion and, therefore, positively charged amino acid residues are likely to be involved in the binding of the substrate. FOR exhibited a significant primary kinetic isotope effect of the apparent Vmax for the deuterated substrate, formaldehyde-d2, which shows that the rate-determining step involves a C[sbnd]H bond break from the aldehyde. The implications of these results for the reaction mechanism of tungsten-containing AORs, are discussed.Accepted Author ManuscriptBT/Biocatalysi

    Legislative amendments, 1996

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    An annotated copy of Senate Bill No. 349: an Act concerning the regulation of hazardous substances, amending P.L.1983. c383, and amending and supplementing P.L.1983, c.315

    The English hermit; or, Unparalleled sufferings and surprising adventures of Mr. Philip Quarll, who was lately discovered on an uninhabited island in the South sea; where he had lived about fifty years without any human assistance.

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    An issue of the 1727 edition in the British museum has the initials P.L. in the title and a dedication, in which the writer claims the authorship of the work, signed Peter Longueville. In the preface (signed P.L.) he denounces the bookseller for having substituted Edward Dorrington's name for his own. For a discussion of the authorship of A. Esdaile's "Author and publisher in 1727: The English hermit", in the Library, 4th ser., v. 2, p. 185-192. Ascribed by some authorities to Alexander Bicknell.Signed: Edward Dorrington.Running title: The English hermit.Mode of access: Internet
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