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| - | [[Image:1os1.jpg|left|200px]] | + | {{Seed}} |
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| | {{STRUCTURE_1os1| PDB=1os1 | SCENE= }} | | {{STRUCTURE_1os1| PDB=1os1 | SCENE= }} |
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| - | '''Structure of Phosphoenolpyruvate Carboxykinase complexed with ATP,Mg, Ca and pyruvate.'''
| + | ===Structure of Phosphoenolpyruvate Carboxykinase complexed with ATP,Mg, Ca and pyruvate.=== |
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| - | ==Overview==
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| - | The 1.8-A resolution structure of the ATP-Mg(2+)-Ca(2+)-pyruvate quinary complex of Escherichia coli phosphoenolpyruvate carboxykinase (PCK) is isomorphous to the published complex ATP-Mg(2+)-Mn(2+)-pyruvate-PCK, except for the Ca(2+) and Mn(2+) binding sites. Ca(2+) was formerly implicated as a possible allosteric regulator of PCK, binding at the active site and at a surface activating site (Glu508 and Glu511). This report found that Ca(2+) bound only at the active site, indicating that there is likely no surface allosteric site. (45)Ca(2+) bound to PCK with a K(d) of 85 micro M and n of 0.92. Glu508Gln Glu511Gln mutant PCK had normal activation by Ca(2+). Separate roles of Mg(2+), which binds the nucleotide, and Ca(2+), which bridges the nucleotide and the anionic substrate, are implied, and the catalytic mechanism of PCK is better explained by studies of the Ca(2+)-bound structure. Partial trypsin digestion abolishes Ca(2+) activation (desensitizes PCK). N-terminal sequencing identified sensitive sites, i.e., Arg2 and Arg396. Arg2Ser, Arg396Ser, and Arg2Ser Arg396Ser (double mutant) PCKs altered the kinetics of desensitization. C-terminal residues 397 to 540 were removed by trypsin when wild-type PCK was completely desensitized. Phe409 and Phe413 interact with residues in the Ca(2+) binding site, probably stabilizing the C terminus. Phe409Ala, DeltaPhe409, Phe413Ala, Delta397-521 (deletion of residues 397 to 521), Arg396(TAA) (stop codon), and Asp269Glu (Ca(2+) site) mutations failed to desensitize PCK and, with the exception of Phe409Ala, appeared to have defects in the synthesis or assembly of PCK, suggesting that the structure of the C-terminal domain is important in these processes. | + | The line below this paragraph, {{ABSTRACT_PUBMED_12837799}}, adds the Publication Abstract to the page |
| | + | (as it appears on PubMed at http://www.pubmed.gov), where 12837799 is the PubMed ID number. |
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| | + | {{ABSTRACT_PUBMED_12837799}} |
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| | ==About this Structure== | | ==About this Structure== |
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| | [[Category: Enzyme mechanism]] | | [[Category: Enzyme mechanism]] |
| | [[Category: Phosphotransfer,calcium,activation]] | | [[Category: Phosphotransfer,calcium,activation]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 04:12:52 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Jul 27 22:21:51 2008'' |
Revision as of 19:21, 27 July 2008
Template:STRUCTURE 1os1
Structure of Phosphoenolpyruvate Carboxykinase complexed with ATP,Mg, Ca and pyruvate.
Template:ABSTRACT PUBMED 12837799
About this Structure
1OS1 is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.
Reference
Mechanisms of activation of phosphoenolpyruvate carboxykinase from Escherichia coli by Ca2+ and of desensitization by trypsin., Sudom A, Walters R, Pastushok L, Goldie D, Prasad L, Delbaere LT, Goldie H, J Bacteriol. 2003 Jul;185(14):4233-42. PMID:12837799
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