1.1.2.B3: quinoprotein methanol dehydrogenase (cytochrome c559)

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For detailed information about quinoprotein methanol dehydrogenase (cytochrome c559), go to the full flat file.

Word Map on EC 1.1.2.B3


+ 2 cytochrome c550 =
+ 2 reduced cytochrome c550 + 2 H+


exaA, More, PedE, PedH, PQQ-alcohol dehydrogenase, PQQ-linked alcohol dehydrogenase, pyrroloquinoline quinone -dependent quinoprotein ethanol dehydrogenase, QEDH, quinoprotein ethanol dehydrogenase


     1 Oxidoreductases
         1.1 Acting on the CH-OH group of donors
             1.1.2 With a cytochrome as acceptor
                1.1.2.B3 quinoprotein methanol dehydrogenase (cytochrome c559)


Engineering on EC 1.1.2.B3 - quinoprotein methanol dehydrogenase (cytochrome c559)

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all pyrroloquinoline quinone-dependent alcohol dehydrogenases contain an unusual disulfide ring formed between adjacent cysteine residues. A mutant enzyme that is lacking this structure is generated by replacing Cys105 and Cys106 with Ala. Heterologously expressed C105A/C106A apoenzyme is successfully converted to enzymatic active holo-enzyme by incorporation of its cofactor pyrroloquinoline quinone (PQQ) in the presence of Ca2+. The enzymatic activity of the mutant enzyme in the artificial dye test with N-methylphenazonium methyl sulfate (PMS) and 2,6-dichlorophenol indophenol (DCPIP) at pH 9 does not depend on an activating amine which is essential for wild type activity under these conditions. The mutant enzyme shows increased Michaelis constants for primary alcohols, while the affinity for the secondary alcohol 2-propanol is unaltered. For all substrates tested the specific activity of the mutant enzyme in the artificial dye test is higher than that found for wild type enzyme. In the ferricyanide test with the natural electron acceptor cytochrome c550 the activity of mutant Cys105Ala/Cys106Ala is 15fold lower than that of wild type enzyme
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