1ius: Difference between revisions

Revision as of 20:26, 2 May 2008

P-HYDROXYBENZOATE HYDROXYLASE COMPLEXED WITH 4-AMINOBENZOATE AT PH 5.0

OverviewOverview

Deprotonation of p-hydroxybenzoate to the phenolate and reprotonation of the hydroxylated dienone intermediate to form the product are essential steps in the reaction catalyzed by p-hydroxybenzoate hydroxylase (PHBH). The mechanism by which protons are transferred in these reactions is not obvious, because the substrate bound in the active site is isolated from solvent. Structure analyses of wild-type and mutant PHBH, with bound p-hydroxybenzoate or p-aminobenzoate, reveal a chain of proton donors and acceptors (the hydroxyl groups of Tyr201 and Tyr385, and two water molecules) that can connect the substrate 4-OH to His72, a surface residue. This chain could provide a pathway for proton transfer to and from the substrate. Using various combinations of pH and substrates, we show that in crystalline PHBH ionizable groups in the chain may rotate and change hydrogen-bond orientation. Molecular dynamics simulations have been used to predict the preferred orientation of hydrogen bonds in the chain as a function of the ionization states of substrate and His72. The calculations suggest that changes in the ionization state of the substrate could be associated with changes in orientation of the hydrogen bonds in the chain. Transfer of water between the chain of proton donors and the solvent also appears to be an essential part of the mechanism that provides reversible transfer of protons during the hydroxylation reaction.

About this StructureAbout this Structure

1IUS is a Single protein structure of sequence from Pseudomonas aeruginosa. Full crystallographic information is available from OCA.

ReferenceReference

pH-dependent structural changes in the active site of p-hydroxybenzoate hydroxylase point to the importance of proton and water movements during catalysis., Gatti DL, Entsch B, Ballou DP, Ludwig ML, Biochemistry. 1996 Jan 16;35(2):567-78. PMID:8555229 Page seeded by OCA on Fri May 2 20:26:39 2008

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OCA

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 [[Image:1ius.gif|left|200px]]
- {{Structure
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-|PDB= 1ius |SIZE=350|CAPTION= <scene name='initialview01'>1ius</scene>, resolution 2.2&Aring;
+The line below this paragraph, containing "STRUCTURE_1ius", creates the "Structure Box" on the page.
-|SITE=
+You may change the PDB parameter (which sets the PDB file loaded into the applet)
-|LIGAND= <scene name='pdbligand=FAD:FLAVIN-ADENINE+DINUCLEOTIDE'>FAD</scene>, <scene name='pdbligand=PAB:4-AMINOBENZOIC+ACID'>PAB</scene>
+or the SCENE parameter (which sets the initial scene displayed when the page is loaded),
-|ACTIVITY= <span class='plainlinks'>[http://en.wikipedia.org/wiki/4-hydroxybenzoate_3-monooxygenase 4-hydroxybenzoate 3-monooxygenase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.14.13.2 1.14.13.2] </span>
+or leave the SCENE parameter empty for the default display.
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-|RELATEDENTRY=
-|RESOURCES=<span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1ius FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1ius OCA], [http://www.ebi.ac.uk/pdbsum/1ius PDBsum], [http://www.rcsb.org/pdb/explore.do?structureId=1ius RCSB]</span>
-}}
 '''P-HYDROXYBENZOATE HYDROXYLASE COMPLEXED WITH 4-AMINOBENZOATE AT PH 5.0'''
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 [[Category: Gatti, D L.]]
 [[Category: Ludwig, M L.]]
-[[Category: oxidoreductase]]
+[[Category: Oxidoreductase]]
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May  2 20:26:39 2008''
-''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Mar 30 21:24:56 2008''