1z93: Difference between revisions

Revision as of 17:19, 3 May 2008

Human Carbonic Anhydrase III:Structural and Kinetic study of Catalysis and Proton Transfer.

OverviewOverview

The residue phenylalanine 198 (Phe 198) is a prominent cause of the lower activity of human carbonic anhydrase III (HCA III) compared with HCA II and other isozymes which have leucine at this site. We report the crystal structures of HCA III and the site-directed mutant F198L HCA III, both at 2.1 A resolution, and the enhancement of catalytic activity by exogenous proton donors containing imidazole rings. Both enzymes had a hexahistidine extension at the carboxy-terminal end, used to aid in purification, that was ordered in the crystal structures bound in the active site cavity of an adjacent symmetry-related enzyme. This observation allowed us to comment on a number of possible binding sites for imidazole and derivatives as exogenous proton donors/acceptors in catalysis by HCA III. Kinetic and structural evidence indicates that the phenyl side chain of Phe 198 in HCA III, about 5 A from the zinc, is a steric constriction in the active site, may cause altered interactions at the zinc-bound solvent, and is a binding site for the activation of catalysis by histidylhistidine. This suggests that sites of activation of the proton-transfer pathway in carbonic anhydrase are closer to the zinc than considered in previous studies.

About this StructureAbout this Structure

1Z93 is a Single protein structure of sequence from Homo sapiens. Full crystallographic information is available from OCA.

ReferenceReference

Human carbonic anhydrase III: structural and kinetic study of catalysis and proton transfer., Duda DM, Tu C, Fisher SZ, An H, Yoshioka C, Govindasamy L, Laipis PJ, Agbandje-McKenna M, Silverman DN, McKenna R, Biochemistry. 2005 Aug 2;44(30):10046-53. PMID:16042381 Page seeded by OCA on Sat May 3 17:19:57 2008

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OCA

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 [[Image:1z93.gif|left|200px]]
- {{Structure
+<!--
-|PDB= 1z93 |SIZE=350|CAPTION= <scene name='initialview01'>1z93</scene>, resolution 2.1&Aring;
+The line below this paragraph, containing "STRUCTURE_1z93", 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=ZN:ZINC+ION'>ZN</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/Carbonate_dehydratase Carbonate dehydratase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=4.2.1.1 4.2.1.1] </span>
+or leave the SCENE parameter empty for the default display.
-|GENE= CA3 ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=9606 Homo sapiens])
+-->
-|DOMAIN=
+{{STRUCTURE_1z93|  PDB=1z93  |  SCENE=  }}
-|RELATEDENTRY=[[1z97|1Z97]]
-|RESOURCES=<span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1z93 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1z93 OCA], [http://www.ebi.ac.uk/pdbsum/1z93 PDBsum], [http://www.rcsb.org/pdb/explore.do?structureId=1z93 RCSB]</span>
-}}
 '''Human Carbonic Anhydrase III:Structural and Kinetic study of Catalysis and Proton Transfer.'''
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 [[Category: Tu, C.]]
 [[Category: Yoshioka, C.]]
-[[Category: carbonic anhydrase iii]]
+[[Category: Carbonic anhydrase iii]]
-[[Category: chemical rescue]]
+[[Category: Chemical rescue]]
-[[Category: proton wire]]
+[[Category: Proton wire]]
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May  3 17:19:57 2008''
-''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Mar 31 01:32:23 2008''