Accepted name: NAD(P)H dehydrogenase (quinone)
Reaction: NAD(P)H + H+ + a quinone = NAD(P)+ + a hydroquinone
Other name(s): menadione reductase; phylloquinone reductase; quinone reductase; dehydrogenase, reduced nicotinamide adenine dinucleotide (phosphate, quinone); DT-diaphorase; flavoprotein NAD(P)H-quinone reductase; menadione oxidoreductase; NAD(P)H dehydrogenase; NAD(P)H menadione reductase; NAD(P)H-quinone dehydrogenase; NAD(P)H-quinone oxidoreductase; NAD(P)H: (quinone-acceptor)oxidoreductase; NAD(P)H: menadione oxidoreductase; NADH-menadione reductase; naphthoquinone reductase; p-benzoquinone reductase; reduced NAD(P)H dehydrogenase; viologen accepting pyridine nucleotide oxidoreductase; vitamin K reductase; diaphorase; reduced nicotinamide-adenine dinucleotide (phosphate) dehydrogenase; vitamin-K reductase; NAD(P)H2 dehydrogenase (quinone); NQO1; QR1; NAD(P)H:(quinone-acceptor) oxidoreductase
Systematic name: NAD(P)H:quinone oxidoreductase
Comments: A flavoprotein. The enzyme catalyses a two-electron reduction and has a preference for short-chain acceptor quinones, such as ubiquinone, benzoquinone, juglone and duroquinone [6]. The animal, but not the plant, form of the enzyme is inhibited by dicoumarol.
1.  di Prisco, G., Casola, L. and Giuditta, A. Purification and properties of a soluble reduced nicotinamide-adenine dinucleotide (phosphate) dehydrogenase from the hepatopancreas of Octopus vulgaris. Biochem. J. 105 (1967) 455–460. [PMID: 4171422]
2.  Giuditta, A. and Strecker, H.J. Purification and some properties of a brain diaphorase. Biochim. Biophys. Acta 48 (1961) 10–19. [PMID: 13705804]
3.  Märki, F. and Martius, C. Vitamin K-Reductase, Darsellung und Eigenschaften. Biochem. Z. 333 (1960) 111–135. [PMID: 13765127]
4.  Misaka, E. and Nakanishi, K. Studies on menadione reductase of bakers' yeast. I. Purification, crystallization and some properties. J. Biochem. (Tokyo) 53 (1963) 465–471.
5.  Wosilait, W.D. The reduction of vitamin K1 by an enzyme from dog liver. J. Biol. Chem. 235 (1960) 1196–1201. [PMID: 13846011]
6.  Sparla, F., Tedeschi, G. and Trost, P. NAD(P)H:(quinone-acceptor) oxidoreductase of tobacco leaves is a flavin mononucleotide-containing flavoenzyme. Plant Physiol. 112 (1996) 249–258. [PMID: 12226388]
7.  Braun, M., Bungert, S. and Friedrich, T. Characterization of the overproduced NADH dehydrogenase fragment of the NADH:ubiquinone oxidoreductase (complex I) from Escherichia coli. Biochemistry 37 (1998) 1861–1867. [PMID: 9485311]
8.  Jaiswal, A.K. Characterization and partial purification of microsomal NAD(P)H:quinone oxidoreductases. Arch. Biochem. Biophys. 375 (2000) 62–68. [PMID: 10683249]
9.  Li, R., Bianchet, M.A., Talalay, P. and Amzel, L.M. The three-dimensional structure of NAD(P)H:quinone reductase, a flavoprotein involved in cancer chemoprotection and chemotherapy: mechanism of the two-electron reduction. Proc. Natl. Acad. Sci. USA 92 (1995) 8846–8850. [PMID: 7568029]
[EC created 1961, transferred 1965 to EC, transferred 2005 to EC]
Transferred entry: juglone 3-monooxygenase, now classified as EC, juglone 3-monooxygenase
[EC created 1989, deleted 2016]
Accepted name: juglone 3-hydroxylase
Reaction: 2 juglone + O2 = 2 3,5-dihydroxy-1,4-naphthoquinone (overall reaction)
(1a) 2 juglone + 2 H2O = 2 naphthalene-1,2,4,8-tetrol
(1b) 2 naphthalene-1,2,4,8-tetrol + O2 = 2 3,5-dihydroxy-1,4-naphthoquinone + 2 H2O
Glossary: juglone = 5-hydroxy-1,4-naphthoquinone
Other name(s): juglone hydroxylase; naphthoquinone hydroxylase; naphthoquinone-hydroxylase
Systematic name: 5-hydroxy-1,4-naphthoquinone,water:oxygen oxidoreductase (3-hydroxylating)
Comments: Even though oxygen is consumed, molecular oxygen is not incorporated into the product. Catalysis starts by incorporation of an oxygen atom from a water molecule into the substrate. The naphthalene-1,2,4,8-tetrol intermediate is then oxidized by molecular oxygen, which is reduced to water. Also acts on 1,4-naphthoquinone, naphthazarin and 2-chloro-1,4-naphthoquinone.
1.  Rettenmaier, H. and Lingens, F. Purification and some properties of two isofunctional juglone hydroxylases from Pseudomonas putida J1. Biol. Chem. Hoppe-Seyler 366 (1985) 637–646. [PMID: 4041238]
[EC created 1989 as EC, transferred 2016 to EC]
Accepted name: 1,4-dihydroxy-2-naphthoyl-CoA hydrolase
Reaction: 1,4-dihydroxy-2-naphthoyl-CoA + H2O = 1,4-dihydroxy-2-naphthoate + CoA
Other name(s): menI (gene name); ydiL (gene name)
Systematic name: 1,4-dihydroxy-2-naphthoyl-CoA hydrolase
Comments: This enzyme participates in the synthesis of menaquinones [4], phylloquinone [3], as well as several plant pigments [1,2]. The enzyme from the cyanobacterium Synechocystis sp. PCC 6803 does not accept benzoyl-CoA or phenylacetyl-CoA as substrates [3].
1.  Muller, W. and Leistner, E. 1,4-Naphthoquinone, an intermediate in juglone (5-hydroxy-1,4-naphthoquinone) biosynthesis. Phytochemistry 15 (1976) 407–410.
2.  Eichinger, D., Bacher, A., Zenk, M.H. and Eisenreich, W. Quantitative assessment of metabolic flux by 13C NMR analysis. Biosynthesis of anthraquinones in Rubia tinctorum. J. Am. Chem. Soc. 121 (1999) 7469–7475.
3.  Widhalm, J.R., van Oostende, C., Furt, F. and Basset, G.J. A dedicated thioesterase of the Hotdog-fold family is required for the biosynthesis of the naphthoquinone ring of vitamin K1. Proc. Natl. Acad. Sci. USA 106 (2009) 5599–5603. [PMID: 19321747]
4.  Chen, M., Ma, X., Chen, X., Jiang, M., Song, H. and Guo, Z. Identification of a hotdog fold thioesterase involved in the biosynthesis of menaquinone in Escherichia coli. J. Bacteriol. 195 (2013) 2768–2775. [PMID: 23564174]
[EC created 2010]
Accepted name: peptidylprolyl isomerase
Reaction: peptidylproline (ω=180) = peptidylproline (ω=0)
Glossary: For definition of ω, click here
Other name(s): PPIase; cyclophilin [misleading, see comments]; peptide bond isomerase; peptidyl-prolyl cis-trans isomerase
Systematic name: peptidylproline cis-trans-isomerase
Comments: The first type of this enzyme found [1] proved to be the protein cyclophilin, which binds the immunosuppressant cyclosporin A. Other distinct families of the enzyme exist, one being FK-506 binding proteins (FKBP) and another that includes parvulin from Escherichia coli. The three families are structurally unrelated and can be distinguished by being inhibited by cyclosporin A, FK-506 and 5-hydroxy-1,4-naphthoquinone, respectively.
1.  Fischer, G. and Bang, H. The refolding of urea-denatured ribonuclease A is catalyzed by peptidyl-prolyl cis-trans isomerase. Biochim. Biophys. Acta 828 (1985) 39–42. [PMID: 3882150]
2.  Fischer, G., Bang, H. and Mech, C. [Determination of enzymatic catalysis for the cis-trans-isomerization of peptide binding in proline-containing peptides] Biomed. Biochim. Acta 43 (1984) 1101–1111. [PMID: 6395866]
3.  Fischer, G., Wittmann-Liebold, B., Lang, K., Kiefhaber, T. and Schmid, F.X. Cyclophilin and peptidyl-prolyl cis-trans isomerase are probably identical proteins. Nature 337 (1989) 476–478. [PMID: 2492638]
4.  Takahashi, N., Hayano, T. and Suzuki, M. Peptidyl-prolyl cis-trans isomerase is the cyclosporin A-binding protein cyclophilin. Nature 337 (1989) 473–475. [PMID: 2644542]
5.  Hennig, L., Christner, C., Kipping, M., Schelbert, B., Rucknagel, K.P., Grabley, S., Kullertz, G. and Fischer, G. Selective inactivation of parvulin-like peptidyl-prolyl cis/trans isomerases by juglone. Biochemistry 37 (1998) 5953–5960. [PMID: 9558330]
6.  Fischer, G. Peptidyl-prolyl cis/trans isomerases and their effectors. Angew. Chem. Int. Ed. Engl. 33 (1994) 1415–1436.
7.  Harrison, R.K. and Stein, R.L. Substrate specificities of the peptidyl prolyl cis-trans isomerase activities of cyclophilin and FK-506 binding protein: evidence for the existence of a family of distinct enzymes. Biochemistry 29 (1990) 3813–3816. [PMID: 1693856]
8.  Eisenmesser, E.Z., Bosco, D.A., Akke, M. and Kern, D. Enzyme dynamics during catalysis. Science 295 (2002) 1520–1523. [PMID: 11859194]
[EC created 1989, modified 2002]