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| {{STRUCTURE_1me5| PDB=1me5 | SCENE= }} | | {{STRUCTURE_1me5| PDB=1me5 | SCENE= }} |
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| '''Crystal Structure of Mycobacterium Tuberculosis Alkylperoxidase AhpD H132Q Mutant'''
| | ===Crystal Structure of Mycobacterium Tuberculosis Alkylperoxidase AhpD H132Q Mutant=== |
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| ==Overview==
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| AhpD, a protein with two cysteine residues, is required for physiological reduction of the Mycobacterium tuberculosis alkylhydroperoxidase AhpC. AhpD also has an alkylhydroperoxidase activity of its own. The AhpC/AhpD system provides critical antioxidant protection, particularly in the absence of the catalase-peroxidase KatG, which is suppressed in most isoniazid-resistant strains. Based on the crystal structure, we proposed recently a catalytic mechanism for AhpD involving a proton relay in which the Glu118 carboxylate group, via His137 and a water molecule, deprotonates the catalytic residue Cys133 (Nunn, C. M., Djordjevic, S., Hillas, P. J., Nishida, C., and Ortiz de Montellano, P. R. (2002) J. Biol. Chem. 277, 20033-20040). A possible role for His132 in subsequent formation of the Cys133-Cys130 disulfide bond was also noted. To test this proposed mechanism, we have expressed the H137F, H137Q, H132F, H132Q, E118F, E118Q, C133S, and C130S mutants of AhpD, determined the crystal structures of the H137F and H132Q mutants, estimated the pKa values of the cysteine residues, and defined the kinetic properties of the mutant proteins. The collective results strongly support the proposed catalytic mechanism for AhpD.
| | The line below this paragraph, {{ABSTRACT_PUBMED_12761216}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 12761216 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_12761216}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Alpha helical]] | | [[Category: Alpha helical]] |
| [[Category: Trimer]] | | [[Category: Trimer]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 00:56:05 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Wed Jul 2 23:46:36 2008'' |
