Enzymes
UniProtKB help_outline | 3 proteins |
Enzyme class help_outline |
|
GO Molecular Function help_outline |
|
Reaction participants Show >> << Hide
- Name help_outline ethylnitronate Identifier CHEBI:77894 Charge 0 Formula C2H5NO2 InChIKeyhelp_outline CPZLOQHKKRZRSD-UHFFFAOYSA-N SMILEShelp_outline C\C=[N+](\O)[O-] 2D coordinates Mol file for the small molecule Search links Involved in 2 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline O2 Identifier CHEBI:15379 (CAS: 7782-44-7) help_outline Charge 0 Formula O2 InChIKeyhelp_outline MYMOFIZGZYHOMD-UHFFFAOYSA-N SMILEShelp_outline O=O 2D coordinates Mol file for the small molecule Search links Involved in 2,709 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline acetaldehyde Identifier CHEBI:15343 (Beilstein: 505984; CAS: 75-07-0) help_outline Charge 0 Formula C2H4O InChIKeyhelp_outline IKHGUXGNUITLKF-UHFFFAOYSA-N SMILEShelp_outline [H]C(C)=O 2D coordinates Mol file for the small molecule Search links Involved in 47 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline chemical entity Identifier CHEBI:24431 Charge Formula Search links Involved in 16,970 reaction(s) Find proteins in UniProtKB for this molecule
- Name help_outline H+ Identifier CHEBI:15378 Charge 1 Formula H InChIKeyhelp_outline GPRLSGONYQIRFK-UHFFFAOYSA-N SMILEShelp_outline [H+] 2D coordinates Mol file for the small molecule Search links Involved in 9,431 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline nitrite Identifier CHEBI:16301 (CAS: 14797-65-0) help_outline Charge -1 Formula NO2 InChIKeyhelp_outline IOVCWXUNBOPUCH-UHFFFAOYSA-M SMILEShelp_outline [O-]N=O 2D coordinates Mol file for the small molecule Search links Involved in 79 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
Cross-references
RHEA:28767 | RHEA:28768 | RHEA:28769 | RHEA:28770 | |
---|---|---|---|---|
Reaction direction help_outline | undefined | left-to-right | right-to-left | bidirectional |
UniProtKB help_outline |
|
|||
EC numbers help_outline | ||||
Gene Ontology help_outline | ||||
MetaCyc help_outline |
Publications
-
Involvement of a flavosemiquinone in the enzymatic oxidation of nitroalkanes catalyzed by 2-nitropropane dioxygenase.
Francis K., Russell B., Gadda G.
2-Nitropropane dioxygenase (EC 1.13.11.32) catalyzes the oxidation of nitroalkanes into their corresponding carbonyl compounds and nitrite. In this study, the ncd-2 gene encoding for the enzyme in Neurospora crassa was cloned, expressed in Escherichia coli, and the resulting enzyme was purified. S ... >> More
2-Nitropropane dioxygenase (EC 1.13.11.32) catalyzes the oxidation of nitroalkanes into their corresponding carbonyl compounds and nitrite. In this study, the ncd-2 gene encoding for the enzyme in Neurospora crassa was cloned, expressed in Escherichia coli, and the resulting enzyme was purified. Size exclusion chromatography, heat denaturation, and mass spectroscopic analyses showed that 2-nitropropane dioxygenase is a homodimer of 80 kDa, containing a mole of non-covalently bound FMN per mole of subunit, and is devoid of iron. With neutral nitroalkanes and anionic nitronates other than propyl-1- and propyl-2-nitronate, for which a non-enzymatic free radical reaction involving superoxide was established using superoxide dismutase, substrate oxidation occurs within the enzyme active site. The enzyme was more specific for nitronates than nitroalkanes, as suggested by the second order rate constant k(cat)/K(m) determined with 2-nitropropane and primary nitroalkanes with alkyl chain lengths between 2 and 6 carbons. The steady state kinetic mechanism with 2-nitropropane, nitroethane, nitrobutane, and nitrohexane, in either the neutral or anionic form, was determined to be sequential, consistent with oxygen reacting with a reduced form of enzyme before release of the carbonyl product. Enzyme-monitored turnover with ethyl nitronate as substrate indicated that the catalytically relevant reduced form of enzyme is an anionic flavin semiquinone, whose formation requires the substrate, but not molecular oxygen, as suggested by anaerobic substrate reduction with nitroethane or ethyl nitronate. Substrate deuterium kinetic isotope effects with 1,2-[(2)H(4)]nitroethane and 1,1,2-[(2)H(3) ethyl nitronate at pH 8 yielded normal and inverse effects on the k(cat)/K(m) value, respectively, and were negligible on the k(cat) value. The k(cat)/K(m) and k(cat) pH profiles with anionic nitronates showed the requirement of an acid, whereas those for neutral nitroalkanes were consistent with the involvement of both an acid and a base in catalysis. The kinetic data reported herein are consistent with an oxidasestyle catalytic mechanism for 2-nitropropane dioxygenase, in which the flavin-mediated oxidation of the anionic nitronates or neutral nitroalkanes and the subsequent oxidation of the enzyme-bound flavin occur in two independent steps. << Less
-
Nitronate monooxygenase, a model for anionic flavin semiquinone intermediates in oxidative catalysis.
Gadda G., Francis K.
Nitronate monooxygenase (NMO), formerly referred to as 2-nitropropane dioxygenase, is an FMN-dependent enzyme that uses molecular oxygen to oxidize (anionic) alkyl nitronates and, in the case of the enzyme from Neurospora crassa, (neutral) nitroalkanes to the corresponding carbonyl compounds and n ... >> More
Nitronate monooxygenase (NMO), formerly referred to as 2-nitropropane dioxygenase, is an FMN-dependent enzyme that uses molecular oxygen to oxidize (anionic) alkyl nitronates and, in the case of the enzyme from Neurospora crassa, (neutral) nitroalkanes to the corresponding carbonyl compounds and nitrite. Over the past 5 years, a resurgence of interest on the enzymology of NMO has driven several studies aimed at the elucidation of the mechanistic and structural properties of the enzyme. This review article summarizes the knowledge gained from these studies on NMO, which has been emerging as a model system for the investigation of anionic flavosemiquinone intermediates in the oxidative catalysis of organic molecules, and for the effect that branching of reaction intermediates has on both the kinetic parameters and isotope effects associated with enzymatic reactions. A comparison of the catalytic mechanism of NMO with other flavin-dependent enzymes that oxidize nitroalkane and nitronates is also presented. << Less
Arch. Biochem. Biophys. 493:53-61(2010) [PubMed] [EuropePMC]
This publication is cited by 1 other entry.
-
Kinetic evidence for an anion binding pocket in the active site of nitronate monooxygenase.
Francis K., Gadda G.
A series of monovalent, inorganic anions and aliphatic aldehydes were tested as inhibitors for Hansenula mrakii and Neurospora crassa nitronate monooxygenase, formerly known as 2-nitropropane dioxygenase, to investigate the structural features that contribute to the binding of the anionic nitronat ... >> More
A series of monovalent, inorganic anions and aliphatic aldehydes were tested as inhibitors for Hansenula mrakii and Neurospora crassa nitronate monooxygenase, formerly known as 2-nitropropane dioxygenase, to investigate the structural features that contribute to the binding of the anionic nitronate substrates to the enzymes. A linear correlation between the volumes of the inorganic anions and their effectiveness as competitive inhibitors of the enzymes was observed in a plot of pK(is)versus the ionic volume of the anion with slopes of 0.041+/-0.001 mM/A(3) and 0.027+/-0.001 mM/A(3) for the H. mrakii and N. crassa enzymes, respectively. Aliphatic aldehydes were weak competitive inhibitors of the enzymes, with inhibition constants that are independent of their alkyl chain lengths. The reductive half reactions of H. mrakii nitronate monooxygenase with primary nitronates containing two to four carbon atoms all showed apparent K(d) values of approximately 5 mM. These results are consistent with the presence of an anion binding pocket in the active site of nitronate monooxygenase that interacts with the nitro group of the substrate, and suggest a minimal contribution of the hydrocarbon chain of the nitronates to the binding of the ligands to the enzyme. << Less
-
Crystal structure of 2-nitropropane dioxygenase complexed with FMN and substrate. Identification of the catalytic base.
Ha J.Y., Min J.Y., Lee S.K., Kim H.S., Kim do J., Kim K.H., Lee H.H., Kim H.K., Yoon H.-J., Suh S.W.
Nitroalkane compounds are widely used in chemical industry and are also produced by microorganisms and plants. Some nitroalkanes have been demonstrated to be carcinogenic, and enzymatic oxidation of nitroalkanes is of considerable interest. 2-Nitropropane dioxygenases from Neurospora crassa and Wi ... >> More
Nitroalkane compounds are widely used in chemical industry and are also produced by microorganisms and plants. Some nitroalkanes have been demonstrated to be carcinogenic, and enzymatic oxidation of nitroalkanes is of considerable interest. 2-Nitropropane dioxygenases from Neurospora crassa and Williopsis mrakii (Hansenula mrakii), members of one family of the nitroalkane-oxidizing enzymes, contain FMN and FAD, respectively. The enzymatic oxidation of nitroalkanes by 2-nitropropane dioxygenase operates by an oxidase-style catalytic mechanism, which was recently shown to involve the formation of an anionic flavin semiquinone. This represents a unique case in which an anionic flavin semiquinone has been experimentally observed in the catalytic pathway for oxidation catalyzed by a flavin-dependent enzyme. Here we report the first crystal structure of 2-nitropropane dioxygenase from Pseudomonas aeruginosa in two forms: a binary complex with FMN and a ternary complex with both FMN and 2-nitropropane. The structure identifies His(152) as the proposed catalytic base, thus providing a structural framework for a better understanding of the catalytic mechanism. << Less
Comments
Some products of the reaction have still not been identified. The IUBMB reaction is: ethylnitronate + O2 = acetaldehyde + nitrite + other products