Accepted name: 2,5-diamino-6-(ribosylamino)-4(3H)-pyrimidinone 5′-phosphate reductase
Reaction: 2,5-diamino-6-(5-phospho-D-ribitylamino)pyrimidin-4(3H)-one + NAD(P)+ = 2,5-diamino-6-(5-phospho-D-ribosylamino)pyrimidin-4(3H)-one + NAD(P)H + H+
Other name(s): 2,5-diamino-6-ribosylamino-4(3H)-pyrimidinone 5′-phosphate reductase; MjaRED; MJ0671 (gene name)
Systematic name: 2,5-diamino-6-(5-phospho-D-ribosylamino)pyrimidin-4(3H)-one:NAD(P)+ oxidoreductase
Comments: The reaction proceeds in the opposite direction. A step in riboflavin biosynthesis, NADPH and NADH function equally well as reductant. Differs from EC [5-amino-6-(5-phosphoribosylamino)uracil reductase] since it does not catalyse the reduction of 5-amino-6-ribosylaminopyrimidine-2,4(1H,3H)-dione 5′-phosphate [1].
1.  Graupner, M., Xu, H. and White, R.H. The pyrimidine nucleotide reductase step in riboflavin and F420 biosynthesis in archaea proceeds by the eukaryotic route to riboflavin. J. Bacteriol. 184 (2002) 1952–1957. [PMID: 11889103]
2.  Chatwell, L., Krojer, T., Fidler, A., Romisch, W., Eisenreich, W., Bacher, A., Huber, R. and Fischer, M. Biosynthesis of riboflavin: structure and properties of 2,5-diamino-6-ribosylamino-4(3H)-pyrimidinone 5′-phosphate reductase of Methanocaldococcus jannaschii. J. Mol. Biol. 359 (2006) 1334–1351. [PMID: 16730025]
[EC created 2010, modified 2011]