View source for 1cnb


==COMPENSATORY PLASTIC EFFECTS IN THE REDESIGN OF PROTEIN-ZINC BINDING SITES==
<StructureSection load='1cnb' size='340' side='right'caption='[[1cnb]], [[Resolution|resolution]] 2.35&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[1cnb]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1CNB OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1CNB FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2.35&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=BME:BETA-MERCAPTOETHANOL'>BME</scene></td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=1cnb FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1cnb OCA], [https://pdbe.org/1cnb PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1cnb RCSB], [https://www.ebi.ac.uk/pdbsum/1cnb PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1cnb ProSAT]</span></td></tr>
</table>
== Disease ==
[https://www.uniprot.org/uniprot/CAH2_HUMAN CAH2_HUMAN] Defects in CA2 are the cause of osteopetrosis autosomal recessive type 3 (OPTB3) [MIM:[https://omim.org/entry/259730 259730]; also known as osteopetrosis with renal tubular acidosis, carbonic anhydrase II deficiency syndrome, Guibaud-Vainsel syndrome or marble brain disease. Osteopetrosis is a rare genetic disease characterized by abnormally dense bone, due to defective resorption of immature bone. The disorder occurs in two forms: a severe autosomal recessive form occurring in utero, infancy, or childhood, and a benign autosomal dominant form occurring in adolescence or adulthood. Autosomal recessive osteopetrosis is usually associated with normal or elevated amount of non-functional osteoclasts. OPTB3 is associated with renal tubular acidosis, cerebral calcification (marble brain disease) and in some cases with mental retardation.<ref>PMID:1928091</ref> <ref>PMID:1542674</ref> <ref>PMID:8834238</ref> <ref>PMID:9143915</ref> <ref>PMID:15300855</ref> 
== Function ==
[https://www.uniprot.org/uniprot/CAH2_HUMAN CAH2_HUMAN] Essential for bone resorption and osteoclast differentiation (By similarity). Reversible hydration of carbon dioxide. Can hydrate cyanamide to urea. Involved in the regulation of fluid secretion into the anterior chamber of the eye.<ref>PMID:10550681</ref> <ref>PMID:11831900</ref> 
== Evolutionary Conservation ==
[[Image:Consurf_key_small.gif|200px|right]]
Check<jmol>
  <jmolCheckbox>
    <scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/cn/1cnb_consurf.spt"</scriptWhenChecked>
    <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview03.spt</scriptWhenUnchecked>
    <text>to colour the structure by Evolutionary Conservation</text>
  </jmolCheckbox>
</jmol>, as determined by [http://consurfdb.tau.ac.il/ ConSurfDB]. You may read the [[Conservation%2C_Evolutionary|explanation]] of the method and the full data available from [http://bental.tau.ac.il/new_ConSurfDB/main_output.php?pdb_ID=1cnb ConSurf].
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== Publication Abstract from PubMed ==
In order to probe the structural importance of zinc ligands in the active site of human carbonic anhydrase II (CAII), we have determined the three-dimensional structures of H94C (in metal-bound form), H94C-BME (i.e., disulfide-linked with beta-mercaptoethanol), H94A, H96C, H119C, and H119D variants of CAII by X-ray crystallographic methods at resolutions of 2.2, 2.35, 2.25, 2.3, 2.2, and 2.25 A, respectively. Each variant crystallizes isomorphously with the wild-type enzyme, in which zinc is tetrahedrally coordinated by H94, H96, H119, and hydroxide ion. The structure of H94C CAII reveals the successful substitution of the naturally occurring histidine zinc ligand by a cysteine thiolate, and metal coordination by C94 is facilitated by the plastic structural response of the beta-sheet superstructure. Importantly, the resulting structure represents the catalytically active form of the enzyme reported previously [Alexander, R. S., Kiefer, L. L., Fierke, C. A., &amp; Christianson, D. W. (1993) Biochemistry 32, 1510-1518]. Contrastingly, the structure of H96C CAII reveals that the engineered side chain does not coordinate to zinc; instead, zinc is tetrahedrally liganded by H94, H119, and two solvent molecules. Thus, the beta-sheet superstructure is not sufficiently plastic in this location to allow C96 to coordinate to the metal ion. Substitution of the thiolate or carboxylate group for wild-type histidine in H119C and H119D CAIIs reveals that tetrahedral metal coordination is maintained in each variant; however, since there is no plastic structural response of the corresponding beta-strand, a longer metal-ligand separation results.(ABSTRACT TRUNCATED AT 250 WORDS)

Structural consequences of redesigning a protein-zinc binding site.,Ippolito JA, Christianson DW Biochemistry. 1994 Dec 27;33(51):15241-9. PMID:7803386<ref>PMID:7803386</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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<div class="pdbe-citations 1cnb" style="background-color:#fffaf0;"></div>

==See Also==
*[[Carbonic anhydrase 3D structures|Carbonic anhydrase 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Homo sapiens]]
[[Category: Large Structures]]
[[Category: Christianson DW]]
[[Category: Ippolito JA]]