![[Feedback]](/icons/banner/feedbackACT.gif){kind=icon}
![[For Subscribers]](/icons/banner/subscriberACT.gif){kind=icon}
![[Archive]](/icons/banner/archiveACT.gif){kind=icon}
![[Search]](/icons/banner/searchACT.gif){kind=icon}
![[Contents]](/icons/banner/tocACT.gif){kind=icon}
|
|
|
|
|
||
Vol. 56, Issue 2, 272-278, August 1999
Divisions of Immunology (S.C., K.W., D.Z.) and Biology (M.S.),
Beckman Research Institute of the City of Hope, Duarte, California;
Department of Medical Oncology, Charing Cross Hospital, London, England
(R.K.); and Department of Chemical Biology, College of Pharmacy,
Rutgers University, Piscataway, New Jersey (C.S.Y.)
The molecular basis of the interaction of DT-diaphorase with a
cytotoxic nitrobenzamide CB1954
[5-(aziridin-1-yl)-2,4-dinitrobenzamide] and five inhibitors was
investigated with wild-type DT-diaphorase (human and rat) and
five mutants [three rat mutants (rY128D, rG150V, rH194D) and two human
mutants (hY155F, hH161Q)]. hY155F and hH161Q were generated to
evaluate a hypothesis that Tyr155 and His161 participate in the
obligatory two-electron transfer reaction of the enzyme. The catalytic
properties of hY155F and hH161Q were compared with a naturally
occurring mutant, hP187S. Pro187 to Ser mutation disturbs the structure
of the central parallel 
-sheet, resulting in a reduction of the
binding affinity of the flavin-adenine dinucleotide prosthetic
group. With NADH as the electron donor and menadione as the electron
acceptor, the kcat values for the wild-type
human DT-diaphorase, hY155F, hH161Q, and hP187S were measured as
66 ± 1, 23 ± 0, 5 ± 0 and 8 ± 2 × 103 min
1, respectively. Because hY155F still
has significant catalytic activity, the hydroxyl group on Tyr155 may
not be as important as proposed. Interestingly, hY155F was found to be
3.3 times more active than the human wild-type DT-diaphorase in the
reduction of CB1954. Computer modeling based on our results suggests
that CB1954 is situated in the active site, with the aziridinyl group pointing toward Tyr155 and the amide group placed near a hydrophobic pocket next to Tyr128. Dicoumarol, Cibacron blue, chrysin,
7,8-dihydroxyflavone, and phenindone are competitive inhibitors of the
enzyme with respect to nicotinamide coenzymes. The binding orientations
of dicoumarol, flavones, and phenindone in the active site of
DT-diaphorase were predicted by results from our inhibitor-binding
studies and computer modeling based on published X-ray structures. Our
studies generated results that explain why dicoumarol is a potent
inhibitor and binds differently from flavones and phenindone in the
active site of DT-diaphorase.
This article has been cited by other articles:
|
|
 |
|
  V. M. Arlt, M. Stiborova, C. J. Henderson, M. R. Osborne, C. A. Bieler, E. Frei, V. Martinek, B. Sopko, C. R. Wolf, H. H. Schmeiser, et al. Environmental Pollutant and Potent Mutagen 3-Nitrobenzanthrone Forms DNA Adducts after Reduction by NAD(P)H:Quinone Oxidoreductase and Conjugation by Acetyltransferases and Sulfotransferases in Human Hepatic Cytosols Cancer Res., April 1, 2005; 65(7): 2644 - 2652. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 G. Asher, J. Lotem, P. Tsvetkov, V. Reiss, L. Sachs, and Y. Shaul p53 hot-spot mutants are resistant to ubiquitin-independent degradation by increased binding to NAD(P)H:quinone oxidoreductase 1 PNAS, December 9, 2003; 100(25): 15065 - 15070. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Stiborova, E. Frei, B. Sopko, K. Sopkova, V. Markova, M. Lankova, T. Kumstyrova, M. Wiessler, and H. H. Schmeiser Human cytosolic enzymes involved in the metabolic activation of carcinogenic aristolochic acid: evidence for reductive activation by human NAD(P)H:quinone oxidoreductase Carcinogenesis, October 1, 2003; 24(10): 1695 - 1703. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P. R. Graves, J. J. Kwiek, P. Fadden, R. Ray, K. Hardeman, A. M. Coley, M. Foley, and T. A. J. Haystead Discovery of Novel Targets of Quinoline Drugs in the Human Purine Binding Proteome Mol. Pharmacol., December 1, 2002; 62(6): 1364 - 1372. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 B. N Ames, I. Elson-Schwab, and E. A Silver High-dose vitamin therapy stimulates variant enzymes with decreased coenzyme binding affinity (increased Km): relevance to genetic disease and polymorphisms Am. J. Clinical Nutrition, April 1, 2002; 75(4): 616 - 658. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Stiborova, E. Frei, B. Sopko, M. Wiessler, and H. H. Schmeiser Carcinogenic aristolochic acids upon activation by DT-diaphorase form adducts found in DNA of patients with Chinese herbs nephropathy Carcinogenesis, April 1, 2002; 23(4): 617 - 625. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 L. B. Sánchez, H. Elmendorf, T. E. Nash, and M. Müller NAD(P)H:menadione oxidoreductase of the amitochondriate eukaryote Giardia lamblia: a simpler homologue of the vertebrate enzyme Microbiology, March 1, 2001; 147(3): 561 - 570. [Abstract] [Full Text]
|
|
|
|
|
|
D. Siegel, A. Anwar, S. L. Winski, J. K. Kepa, K. L. Zolman, and D. Ross Rapid Polyubiquitination and Proteasomal Degradation of a Mutant Form of NAD(P)H:Quinone Oxidoreductase 1 Mol. Pharmacol., February 1, 2001; 59(2): 263 - 268. [Abstract] [Full Text]
|
|
|
|
|
|
M. Faig, M. A. Bianchet, P. Talalay, S. Chen, S. Winski, D. Ross, and L. M. Amzel Structures of recombinant human and mouse NAD(P)H:quinone oxidoreductases: Species comparison and structural changes with substrate binding and release PNAS, March 28, 2000; 97(7): 3177 - 3182. [Abstract] [Full Text] [PDF]
|
|
 |
 |
 |
|
 |
 |
 |
