Kinetic and chemical mechanisms of shikimate dehydrogenase from Mycobacterium tuberculosis
Mycobacterium tuberculosis shikimate dehydrogenase ( MtbSD) catalyzes the fourth reaction in the shikimate pathway, the NADPH-dependent reduction of 3-dehydroshikimate. To gather information on the kinetic mechanism, initial velocity patterns, product inhibition, and primary deuterium kinetic isotop...
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Published in | Archives of biochemistry and biophysics Vol. 457; no. 2; pp. 123 - 133 |
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Main Authors | , , , , , |
Format | Journal Article |
Language | English |
Published |
United States
Elsevier Inc
15.01.2007
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Subjects | |
Online Access | Get full text |
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Summary: | Mycobacterium tuberculosis shikimate dehydrogenase (
MtbSD) catalyzes the fourth reaction in the shikimate pathway, the NADPH-dependent reduction of 3-dehydroshikimate. To gather information on the kinetic mechanism, initial velocity patterns, product inhibition, and primary deuterium kinetic isotope effect studies were performed and the results suggested a steady-state ordered bi-bi kinetic mechanism. The magnitudes of both primary and solvent kinetic isotope effects indicated that the hydride transferred from NADPH and protons transferred from the solvent in the catalytic cycle are not significantly rate limiting in the overall reaction. Proton inventory analysis indicates that one proton gives rise to solvent isotope effects. Multiple isotope effect studies indicate that both hydride and proton transfers are concerted. The pH profiles revealed that acid/base chemistry takes place in catalysis and substrate binding. The
MtbSD 3D model was obtained
in silico by homology modeling. Kinetic and chemical mechanisms for
MtbSD are proposed on the basis of experimental data. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0003-9861 1096-0384 |
DOI: | 10.1016/j.abb.2006.11.015 |