Nitrate reductase

Function

Nitrate reductase (NR) catalyzes the reduction of NO₃ to NO₂ using NADPH^[1]. NR active site contains Mo atom. Four types of NR are known:
eukaryotic assimilatory NR
bacterial cytoplasmic assimilatory (NAC)
bacterial membrane-bound respiratory (NAR)
bacterial periplasmic dissimilatory (NAP).
The cofactors of NR are Molybdopterin (MPT) in eukaryotic NR and bis-Molybdopterin guanine dinucleotide (MGD) in bacterial NR.

Structural highlights

. NAP active site includes a . The planery NO3 molecule is guided to the active site by a funnel leading to the Mo atom^[2].