EC 1.5.1.50     
Accepted name: dihydromonapterin reductase
Reaction: 5,6,7,8-tetrahydromonapterin + NADP+ = 7,8-dihydromonapterin + NADPH + H+
Glossary: 7,8-dihydromonapterin = 2-amino-6-[(1S,2S)-1,2,3-trihydroxypropyl]-7,8-dihydropteridin-4(3H)-one
Other name(s): FolM; H2-MPt reductase
Systematic name: 5,6,7,8-tetrahydromonapterin:NADP+ oxidoreductase
Comments: The enzyme, found in many Gram negative bacteria, also slowly reduces 7,8-dihydrofolate to 5,6,7,8-tetrahydrofolate (cf. EC 1.5.1.3, dihydrofolate reductase). The enzyme has no activity with NADH.
References:
1.  Pribat, A., Blaby, I.K., Lara-Nunez, A., Gregory, J.F., 3rd, de Crecy-Lagard, V. and Hanson, A.D. FolX and FolM are essential for tetrahydromonapterin synthesis in Escherichia coli and Pseudomonas aeruginosa. J. Bacteriol. 192 (2010) 475–482. [PMID: 19897652]
[EC 1.5.1.50 created 2015]
 
 
EC 5.1.99.7     
Accepted name: dihydroneopterin triphosphate 2′-epimerase
Reaction: 7,8-dihydroneopterin 3′-triphosphate = 7,8-dihydromonapterin 3′-triphosphate
Glossary: 7,8-dihydroneopterin 3′-triphosphate = (2R,3S)-3-(2-amino-4-oxo-3,4,7,8-tetrahydropteridin-6-yl)-2,3-dihydroxypropyl triphosphate
7,8-dihydromonapterin 3′-triphosphate = (2S,3S)-3-(2-amino-4-oxo-3,4,7,8-tetrahydropteridin-6-yl)-2,3-dihydroxypropyl triphosphate
Other name(s): D-erythro-7,8-dihydroneopterin triphosphate epimerase; folX (gene name)
Systematic name: 7,8-dihydroneopterin 3′-triphosphate 2′-epimerase
Comments: The enzyme, found in gammaproteobacteria, has almost no activity with 7,8-dihydroneopterin [2].
References:
1.  Ahn, C., Byun, J. and Yim, J. Purification, cloning, and functional expression of dihydroneopterin triphosphate 2′-epimerase from Escherichia coli. J. Biol. Chem. 272 (1997) 15323–15328. [PMID: 9182560]
2.  Haussmann, C., Rohdich, F., Schmidt, E., Bacher, A. and Richter, G. Biosynthesis of pteridines in Escherichia coli. Structural and mechanistic similarity of dihydroneopterin-triphosphate epimerase and dihydroneopterin aldolase. J. Biol. Chem. 273 (1998) 17418–17424. [PMID: 9651328]
[EC 5.1.99.7 created 2015]
 
 
EC 5.1.99.8     
Accepted name: 7,8-dihydroneopterin epimerase
Reaction: 7,8-dihydroneopterin = 7,8-dihydromonapterin
Glossary: 7,8-dihydroneopterin = 2-amino-6-[(1S,2R)-1,2,3-trihydroxypropyl]-7,8-dihydropteridin-4(3H)-one
7,8-dihydromonapterin = 2-amino-6-[(1S,2S)-1,2,3-trihydroxypropyl]-7,8-dihydropteridin-4(3H)-one
Systematic name: 7,8-dihydroneopterin 2′-epimerase
Comments: The enzyme, which has been characterized in bacteria and plants, also has the activity of EC 4.1.2.25, dihydroneopterin aldolase. The enzyme from the bacterium Mycobacterium tuberculosis has an additional oxygenase function (EC 1.13.11.81, 7,8-dihydroneopterin oxygenase) [4].
References:
1.  Haussmann, C., Rohdich, F., Schmidt, E., Bacher, A. and Richter, G. Biosynthesis of pteridines in Escherichia coli. Structural and mechanistic similarity of dihydroneopterin-triphosphate epimerase and dihydroneopterin aldolase. J. Biol. Chem. 273 (1998) 17418–17424. [PMID: 9651328]
2.  Goyer, A., Illarionova, V., Roje, S., Fischer, M., Bacher, A. and Hanson, A.D. Folate biosynthesis in higher plants. cDNA cloning, heterologous expression, and characterization of dihydroneopterin aldolases. Plant Physiol. 135 (2004) 103–111. [PMID: 15107504]
3.  Czekster, C.M. and Blanchard, J.S. One substrate, five products: reactions catalyzed by the dihydroneopterin aldolase from Mycobacterium tuberculosis. J. Am. Chem. Soc. 134 (2012) 19758–19771. [PMID: 23150985]
4.  Blaszczyk, J., Lu, Z., Li, Y., Yan, H. and Ji, X. Crystallographic and molecular dynamics simulation analysis of Escherichia coli dihydroneopterin aldolase. Cell Biosci 4:52 (2014). [PMID: 25264482]
[EC 5.1.99.8 created 2015]