Resolution of two native monomeric 90Â kDa nitrate reductase active proteins from Shewanella gelidimarina and the sequence of two napA genes

► Two monomeric 90 kDa nitrate reductase active proteins from Shewanella gelidimarina. ► Sequence of napA from napEDABC-type operon and napA from NapDAGHB-type operon. ► Isolation of NAP as NapA or NapAB correlated with NapA P47E amino acid substitution.