Enzymes
| UniProtKB help_outline | 2 proteins |
| Enzyme class help_outline |
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- Name help_outline mycothiol Identifier CHEBI:16768 (Beilstein: 9308053; CAS: 192126-76-4) help_outline Charge 0 Formula C17H30N2O12S InChIKeyhelp_outline MQBCDKMPXVYCGO-FQBKTPCVSA-N SMILEShelp_outline CC(=O)N[C@@H](CS)C(=O)N[C@@H]1[C@@H](O)[C@H](O)[C@@H](CO)O[C@@H]1O[C@H]1[C@H](O)[C@@H](O)[C@H](O)[C@@H](O)[C@H]1O 2D coordinates Mol file for the small molecule Search links Involved in 5 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline NAD+ Identifier CHEBI:57540 (Beilstein: 3868403) help_outline Charge -1 Formula C21H26N7O14P2 InChIKeyhelp_outline BAWFJGJZGIEFAR-NNYOXOHSSA-M SMILEShelp_outline NC(=O)c1ccc[n+](c1)[C@@H]1O[C@H](COP([O-])(=O)OP([O-])(=O)OC[C@H]2O[C@H]([C@H](O)[C@@H]2O)n2cnc3c(N)ncnc23)[C@@H](O)[C@H]1O 2D coordinates Mol file for the small molecule Search links Involved in 1,186 reaction(s) Find molecules that contain or resemble this structure 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 mycothione Identifier CHEBI:16086 (Beilstein: 6953243) help_outline Charge 0 Formula C34H58N4O24S2 InChIKeyhelp_outline YKSIHFDRGQQOCJ-LHHMOHDTSA-N SMILEShelp_outline CC(=O)N[C@@H](CSSC[C@H](NC(C)=O)C(=O)N[C@@H]1[C@@H](O)[C@H](O)[C@@H](CO)O[C@@H]1O[C@H]1[C@H](O)[C@@H](O)[C@H](O)[C@@H](O)[C@H]1O)C(=O)N[C@@H]1[C@@H](O)[C@H](O)[C@@H](CO)O[C@@H]1O[C@H]1[C@H](O)[C@@H](O)[C@H](O)[C@@H](O)[C@H]1O 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 NADH Identifier CHEBI:57945 (Beilstein: 3869564) help_outline Charge -2 Formula C21H27N7O14P2 InChIKeyhelp_outline BOPGDPNILDQYTO-NNYOXOHSSA-L SMILEShelp_outline NC(=O)C1=CN(C=CC1)[C@@H]1O[C@H](COP([O-])(=O)OP([O-])(=O)OC[C@H]2O[C@H]([C@H](O)[C@@H]2O)n2cnc3c(N)ncnc23)[C@@H](O)[C@H]1O 2D coordinates Mol file for the small molecule Search links Involved in 1,116 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
Cross-references
| RHEA:12689 | RHEA:12690 | RHEA:12691 | RHEA:12692 | |
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| Reaction direction help_outline | undefined | left-to-right | right-to-left | bidirectional |
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Publications
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Mycobacterium tuberculosis mycothione reductase: pH dependence of the kinetic parameters and kinetic isotope effects.
Patel M.P., Blanchard J.S.
The recent identification of the enzyme in Mycobacterium tuberculosis that catalyzes the NADPH-dependent reduction of the unique low molecular weight disulfide mycothione, mycothione reductase, has led us to examine the mechanism of catalysis in greater detail. The pH dependence of the kinetic par ... >> More
The recent identification of the enzyme in Mycobacterium tuberculosis that catalyzes the NADPH-dependent reduction of the unique low molecular weight disulfide mycothione, mycothione reductase, has led us to examine the mechanism of catalysis in greater detail. The pH dependence of the kinetic parameters V and V/K for NADPH, NADH, and an active analogue of mycothione disulfide, des-myo-inositol mycothione disulfide, has been determined. An analysis of the pH profiles has allowed the tentative assignment of catalytically significant residues crucial to the mechanism of disulfide reduction, namely, the His444-Glu449 ion pair and Cys39. Solvent kinetic isotope effects were observed on V and V/K(DIMSSM), yielding values of 1.7 +/- 0.2 and 1.4 +/-0.2, respectively, but not on V/K(NADPH). Proton inventory studies (V versus mole fraction of D(2)O) were linear, indicative of a single proton transfer in a solvent isotopically sensitive step. Steady-state primary deuterium kinetic isotope effects on V have been determined using NADPH and NADH, yielding values of 1.27 +/- 0.03 and 1.66 +/-0.14, respectively. The pre-steady-state primary deuterium kinetic isotope effect on enzyme reduction has values of 1.82 +/- 0.04 and 1.59 +/-0.06 for NADPH and NADH, respectively. The steady-state primary deuterium kinetic isotope effect using NADH coincide with that obtained under single turnover conditions, suggesting the complete expression of the intrinsic primary kinetic isotope effect. Rapid reaction studies on the reductive half-reaction using NADPH and NADH yielded maximal rates of 129 +/- 2 and 20 +/-1 s(-1), respectively, while similar studies of the oxidation of the two-electron reduced enzyme by mycothiol disulfide yielded a maximum rate of 190 +/-10 s(-1). These data suggest a unique flavoprotein disulfide mechanism in which the rate of the oxidative half-reaction is slightly faster than the rate of the reductive half-reaction. << Less
Biochemistry 40:5119-5126(2001) [PubMed] [EuropePMC]
This publication is cited by 1 other entry.
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Expression, purification, and characterization of Mycobacterium tuberculosis mycothione reductase.
Patel M.P., Blanchard J.S.
Mycothione reductase from the human pathogen Mycobacterium tuberculosis has been cloned, expressed in Mycobacterium smegmatis, and purified 145-fold to homogeneity in 43% yield. Amino acid sequence alignment of mycothione reductase with the functionally homologous glutathione and trypanothione red ... >> More
Mycothione reductase from the human pathogen Mycobacterium tuberculosis has been cloned, expressed in Mycobacterium smegmatis, and purified 145-fold to homogeneity in 43% yield. Amino acid sequence alignment of mycothione reductase with the functionally homologous glutathione and trypanothione reductase indicates conservation of the catalytically important redox-active disulfide, histidine-glutamate ion pair, and regions involved in binding both the FAD cofactor and the substrate NADPH. The homogeneous 50 kDa subunit enzyme exists as a homodimer and is NADPH-dependent and highly specific for the structurally unique low-molecular mass disulfide, mycothione, exhibiting Michaelis constants of 8 and 73 microM for NADPH and mycothione, respectively. HPLC analysis indicated the presence of 1 mol of bound FAD per monomer as the cofactor exhibiting an absorption spectrum with a lambda(max) at 462 nm with an extinction coefficient of 11 300 M(-)(1) cm(-)(1). The reductive titration of the enzyme with NADH indicates the presence of a charge-transfer complex of one of the presumptive catalytic thiolates and FAD absorbing at ca. 530 nm. Reaction with serially truncated mycothione and other disulfides and pyridine nucleotide analogues indicates a strict minimal disulfide substrate requirement for the glucosamine moiety of mycothione. The enzyme exhibits bi-bi ping-pong kinetics with both disulfide and quinone substrates. Transhydrogenase activity is observed using NADH and thio-NADP(+), confirming the kinetic mechanism. We suggest mycothione reductase as the newest member of the class I flavoprotein disulfide reductase family of oxidoreductases. << Less
Biochemistry 38:11827-11833(1999) [PubMed] [EuropePMC]
This publication is cited by 1 other entry.