Marga Dijkstra

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Several reaction rate constants in the catalytic cycle of methanol dehydrogenase (EC 1.1.99.8) in vitro were determined with stopped-flow spectrophotometry. The studies revealed that the high pH required for adequate activity of the enzyme is related to the strong pH dependency of the oxidation rates of the reduced and semiquinone enzyme forms, MDHred and(More)
Quinoprotein alcohol dehydrogenases can be inactivated by cyclopropanol, cyclopropanone hydrate, and, depending on whether they can oxidize secondary alcohols, also by cyclopropanone ethyl hemiketal. Only enzyme molecules containing the oxidized coenzyme (PQQ), but not those with the coenzyme in the semiquinone form (PQQH), become inactivated with these(More)
Ferricytochrome cL isolated from Hyphomicrobium X is an electron acceptor in assays for homologous methanol dehydrogenase (MDH), albeit a poor one compared with artificial dyes. The intermediates of MDH seen during the reaction are identical with those observed with Wurster's Blue as electron acceptor, indicating that the reaction cycles are similar. The(More)
Hyphomicrobium X, grown on methanol with O2 or nitrate as electron acceptor, contains two major soluble cytochromes c. These were isolated in electrophoretically homogeneous form. They are related to cytochromes c already described for other methylotrophic bacteria and designated cytochromes cH and cL (properties indicated in that order) in view of the(More)
A mass-tagged N-mesityl imidazolinium salt with four additional -CH(2)NCy(2) substituents was synthesized, leading to a molecular mass of nearly 1100 g mol(-1) in the corresponding carbene ligand. This mass-tagged ligand was used to generate the respective Grubbs II and Grubbs-Hoveyda type complexes. The catalytic activity of the latter complex was tested(More)
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