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| | {{STRUCTURE_1vj3| PDB=1vj3 | SCENE= }} | | {{STRUCTURE_1vj3| PDB=1vj3 | SCENE= }} |
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| - | '''STRUCTURAL STUDIES ON BIO-ACTIVE COMPOUNDS. CRYSTAL STRUCTURE AND MOLECULAR MODELING STUDIES ON THE PNEUMOCYSTIS CARINII DIHYDROFOLATE REDUCTASE COFACTOR COMPLEX WITH TAB, A HIGHLY SELECTIVE ANTIFOLATE.'''
| + | ===STRUCTURAL STUDIES ON BIO-ACTIVE COMPOUNDS. CRYSTAL STRUCTURE AND MOLECULAR MODELING STUDIES ON THE PNEUMOCYSTIS CARINII DIHYDROFOLATE REDUCTASE COFACTOR COMPLEX WITH TAB, A HIGHLY SELECTIVE ANTIFOLATE.=== |
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| - | ==Overview==
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| - | The crystal structure of the ternary complex of NADPH, the potent antifolate [2, 4-diamino-5- inverted question mark3-[3-(2-acetyloxyethyl)-3-benzyltriazen-1-yl]-4 -chloroph enyl inverted question mark-6-ethylpyrimidine] (TAB, 1) and Pneumocystis carinii dihydrofolate reductase (pcDHFR), refined to 2.1 A resolution, reveals that TAB binds similar to the antifolates trimethoprim and methotrexate. These data also reveal multiple conformations for the binding geometry of TAB with two preferred orientations of the acetyloxy and benzyl groups that results from a 180 degrees rotation about the N2-N3 triazenyl bond. The methyl of the acetyloxy and benzyl ring of TAB probes large hydrophobic regions of the p-aminobenzoyl folate binding pocket of the active site, in particular the region near Phe69, which is unique to the pcDHFR sequence. These results confirm prior molecular modeling investigations of the binding of TAB to pcDHFR that identified four low-energy binding geometries, two involving rotations about the terminal N(2)-N(3) triazenyl linkage and two involving atropisomerism about the pivotal pyrimethamine-phenyl bond. The primary differences in the molecular dynamics (MD) models and those observed in this crystal complex result from small conformational changes in active-site residues on energy minimization. However, two MD models place the acetyloxy and benzyl ring groups in a region of the active site between the cofactor-binding region and the p-aminobenzoyl folate pocket; an orientation never observed in any DHFR crystal structure to date. These conformers interact with solvent near the enzyme surface and are probably not observed due to the loss of specific hydrogen bonds with the enzyme. The high species pcDHFR selectivity of TAB could be the result of ligand flexibility that enables multiple binding orientations at the enzyme active site. Further modification of the acetyloxy region of TAB could increase its potency and selectivity for pcDHFR.
| + | The line below this paragraph, {{ABSTRACT_PUBMED_10736154}}, adds the Publication Abstract to the page |
| | + | (as it appears on PubMed at http://www.pubmed.gov), where 10736154 is the PubMed ID number. |
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| | + | {{ABSTRACT_PUBMED_10736154}} |
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| | ==About this Structure== | | ==About this Structure== |
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| | [[Category: Nadph]] | | [[Category: Nadph]] |
| | [[Category: Tab]] | | [[Category: Tab]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 12:35:08 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 17:51:25 2008'' |
Revision as of 14:51, 28 July 2008
Template:STRUCTURE 1vj3
STRUCTURAL STUDIES ON BIO-ACTIVE COMPOUNDS. CRYSTAL STRUCTURE AND MOLECULAR MODELING STUDIES ON THE PNEUMOCYSTIS CARINII DIHYDROFOLATE REDUCTASE COFACTOR COMPLEX WITH TAB, A HIGHLY SELECTIVE ANTIFOLATE.
Template:ABSTRACT PUBMED 10736154
About this Structure
1VJ3 is a Single protein structure of sequence from Pneumocystis carinii. This structure supersedes the now removed PDB entry 1d8r. Full crystallographic information is available from OCA.
Reference
Structural studies on bioactive compounds. 30. Crystal structure and molecular modeling studies on the Pneumocystis carinii dihydrofolate reductase cofactor complex with TAB, a highly selective antifolate., Cody V, Chan D, Galitsky N, Rak D, Luft JR, Pangborn W, Queener SF, Laughton CA, Stevens MF, Biochemistry. 2000 Apr 4;39(13):3556-64. PMID:10736154
Page seeded by OCA on Mon Jul 28 17:51:25 2008
