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1.6.5.10: NADPH dehydrogenase (quinone)

This is an abbreviated version!
For detailed information about NADPH dehydrogenase (quinone), go to the full flat file.

Word Map on EC 1.6.5.10

Reaction

NADPH
+
H+
 +
a quinone
=
NADP+
 +
a quinol

Synonyms

AKR1C9, ArsH, azoreductase, CBR4, dehydrogenase, reduced nicotinamide adenine dinucleotide phosphate (quinone), EC 1.6.99.6, MdaB, More, NADPH oxidase, NADPH quinone oxidoreductase, NADPH quinone oxidoreductase 1, NADPH quinone reductase, NADPH-dependent quinone reductase, NADPH-quinone oxidoreductase, NADPH:quinone oxidoreductase 1, NQO1, PA1225, PpAzoR, XAC2229, Zta1p

ECTree

     1 Oxidoreductases
         1.6 Acting on NADH or NADPH
             1.6.5 With a quinone or similar compound as acceptor
                1.6.5.10 NADPH dehydrogenase (quinone)

General Information

General Information on EC 1.6.5.10 - NADPH dehydrogenase (quinone)

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GENERAL INFORMATION
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
evolution
-
the enzyme is a member of the family of NADPH-dependent FMN reductases
malfunction
-
arsH mutants are sensitive to the oxidizing agent menadione
metabolism
lack of inhibition by NADP+ versus NADPH at saturating concentrations of 1,4-benzoquinone is consistent with a ping-pong bi-bi mechanism. The reductive half-reaction at pH 6.0 has Kd values of 0.07 mM with NADPH and 1.8 mM with NADH. The kred for flavin reduction is independent of pH with values of about 10 per s with NADPH and about 5 per s with NADH. Hydride transfer from NADPH to FAD is fully rate limiting for the overall turnover of the enzyme
physiological function
additional information
-
although the enzyme is able to stabilize the anionic semiquinone form of the FMN, reduction of quinones involves the hydroquinone form of the flavin cofactor, and the enzymatic reaction occurs through a ping pong-type mechanism. ArsH is able to catalyze one-electron reactions (oxygen and cytocrome c reduction), involving the FMN semiquinone form, but with lower efficiency