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5ca2

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[[Image:5ca2.gif|left|200px]]
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{{STRUCTURE_5ca2| PDB=5ca2 | SCENE= }}
{{STRUCTURE_5ca2| PDB=5ca2 | SCENE= }}
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'''CONFORMATIONAL MOBILITY OF HIS-64 IN THE THR-200 (RIGHT ARROW) SER MUTANT OF HUMAN CARBONIC ANHYDRASE II'''
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===CONFORMATIONAL MOBILITY OF HIS-64 IN THE THR-200 (RIGHT ARROW) SER MUTANT OF HUMAN CARBONIC ANHYDRASE II===
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==Overview==
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The three-dimensional structure of the Thr-200----Ser (T200S) mutant of human carbonic anhydrase II (CAII) has been determined by X-ray crystallographic methods at 2.1-A resolution. This particular mutant of CAII exhibits CO2 hydrase activity that is comparable to that of the wild-type enzyme with a 2-fold stabilization of the E.HCO3- complex and esterase activity that is 4-fold greater than that of the wild-type enzyme. The structure of the mutant enzyme reveals no significant local changes accompanying the conservative T200S substitution, but an important nonlocal structural change is evident: the side chain of catalytic residue His-64 rotates away from the active site by 105 degrees about chi 1 and apparently displaces a water molecule. The displaced water molecule is present in the wild-type enzyme; however, the electron density into which this water is built is interpretable as an alternate conformation of His-64 with 10-20% occupancy. The rate constants for proton transfer from the zinc-water ligand to His-64 and from His-64 to bulk solvent are maintained in the T200S variant; therefore, if His-64 is conformationally mobile about chi 1 and/or chi 2 during catalysis, compensatory changes in solvent configuration must sustain efficient proton transfer.
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(as it appears on PubMed at http://www.pubmed.gov), where 1909891 is the PubMed ID number.
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{{ABSTRACT_PUBMED_1909891}}
==About this Structure==
==About this Structure==
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[[Category: Alexander, R S.]]
[[Category: Alexander, R S.]]
[[Category: Christianson, D W.]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 22:32:21 2008''
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Jul 3 13:57:32 2008''

Revision as of 10:57, 3 July 2008

Image:5ca2.png

Template:STRUCTURE 5ca2

CONFORMATIONAL MOBILITY OF HIS-64 IN THE THR-200 (RIGHT ARROW) SER MUTANT OF HUMAN CARBONIC ANHYDRASE II

Template:ABSTRACT PUBMED 1909891

About this Structure

5CA2 is a Single protein structure of sequence from Homo sapiens. Full crystallographic information is available from OCA.

Reference

Conformational mobility of His-64 in the Thr-200----Ser mutant of human carbonic anhydrase II., Krebs JF, Fierke CA, Alexander RS, Christianson DW, Biochemistry. 1991 Sep 24;30(38):9153-60. PMID:1909891

Page seeded by OCA on Thu Jul 3 13:57:32 2008

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