The profiles do not make a distinction between class I, class II oxidoreductases, NADH peroxidase and NADH oxidase
Strong sequence homology exists between NADH peroxidase (NadPrx) and NADH oxidase (NadOxd) which can suggest that both genes originally diverged from a common ancestral sequence. NadPrx adn NadOxd share low level of identity with other members of the flavoprotein disulfide reductase classes.
NadPrx as well as other pyridine nucleotide-disulphide reductases (PNDR) use the isoalloxazine ring of FAD to shuttle reducing equivalents from NAD(P)H to a Cys residue that is usually a part of a redox-active disulphide bridge. In a second step, the reduced disulphide reduces the substrate.
Particular residues have been found to be highly conserved in within the FAD/NAD binding domain.
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