NADP-dependent quinone oxidoreductase

These findings led to the proposition that the veratryl alcohol is degraded via the quinone intermediates (Figure 5) to CO2 through a series of transformations involving lignin peroxidase, perhydroxy radicals and the NADP-dependent aryl alcohol oxidoreductase. Veratraldehyde, the major product of lignin peroxidase catalyzed veratryl alcohol oxidation, is rapidly reduced back to veratryl alcohol it is the further metabolism of the side products of the oxidative process, viz. the quinones and lactones, that drives the overall transformation towards completion (34). 

Isolated oxidoreductases always depend on cofactors for the transfer of electrons. Enzyme groups which are well characterized with respect to their biochemistry are those requiring the nicotinamide coenzymes NAD or NADP, the flavins FAD or FMN and the ortho-quinoids such as pyrroloquinoline quinone (PQQ) or trihydroxy-phenylalanine (TOPA). 

Clostridium thermoaceticum contains the so-called AMAPOR (artificial-media-tor-accepting pyridine-nucleotide oxidoreductases), which are useful for electro-microbial regeneration of all four forms of pyridine nucleotides, too. An NADP(H) dependent AMAPOR from C. thermoaceticum has been purified and characterized [104]. It is able to react with rather different artificial mediators such as viologens or quinones, for example 1,4-benzoquinone, anthraquinone-2,6-disulfonate, or 2,6-dichloro-indophenol. 

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