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| | {{STRUCTURE_1w2i| PDB=1w2i | SCENE= }} | | {{STRUCTURE_1w2i| PDB=1w2i | SCENE= }} |
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| - | '''CRYSTAL STRUCTUORE OF ACYLPHOSPHATASE FROM PYROCOCCUS HORIKOSHII COMPLEXED WITH FORMATE'''
| + | ===CRYSTAL STRUCTUORE OF ACYLPHOSPHATASE FROM PYROCOCCUS HORIKOSHII COMPLEXED WITH FORMATE=== |
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| - | ==Overview==
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| - | Acylphosphatases catalyze the hydrolysis of the carboxyl-phosphate bond in acyl phosphates. Although acylphosphatase-like sequences are found in all three domains of life, no structure of acylphosphatase has been reported for bacteria and archaea so far. Here, we report the characterization of enzymatic activities and crystal structure of an archaeal acylphosphatase. A putative acylphosphatase gene (PhAcP) was cloned from the genomic DNA of Pyrococcus horikoshii and was expressed in Escherichia coli. Enzymatic parameters of the recombinant PhAcP were measured using benzoyl phosphate as the substrate. Our data suggest that, while PhAcP is less efficient than other mammalian homologues at 25 degrees C, the thermophilic enzyme is fully active at the optimal growth temperature (98 degrees C) of P. horikoshii. PhAcP is extremely stable; its apparent melting temperature was 111.5 degrees C and free energy of unfolding at 25 degrees C was 54 kJ mol(-)(1). The 1.5 A crystal structure of PhAcP adopts an alpha/beta sandwich fold that is common to other acylphosphatases. PhAcP forms a dimer in the crystal structure via antiparallel association of strand 4. Structural comparison to mesophilic acylphosphatases reveals significant differences in the conformation of the L5 loop connecting strands 4 and 5. The extreme thermostability of PhAcP can be attributed to an extensive ion-pair network consisting of 13 charge residues on the beta sheet of the protein. The reduced catalytic efficiency of PhAcP at 25 degrees C may be due to a less flexible active-site residue, Arg20, which forms a salt bridge to the C-terminal carboxyl group. New insights into catalysis were gained by docking acetyl phosphate to the active site of PhAcP.
| + | The line below this paragraph, {{ABSTRACT_PUBMED_15779887}}, adds the Publication Abstract to the page |
| | + | (as it appears on PubMed at http://www.pubmed.gov), where 15779887 is the PubMed ID number. |
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| | + | {{ABSTRACT_PUBMED_15779887}} |
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| | ==About this Structure== | | ==About this Structure== |
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| | [[Category: Stability]] | | [[Category: Stability]] |
| | [[Category: Thermophilic]] | | [[Category: Thermophilic]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 13:03:49 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Jul 27 21:50:11 2008'' |
Revision as of 18:50, 27 July 2008
Template:STRUCTURE 1w2i
CRYSTAL STRUCTUORE OF ACYLPHOSPHATASE FROM PYROCOCCUS HORIKOSHII COMPLEXED WITH FORMATE
Template:ABSTRACT PUBMED 15779887
About this Structure
1W2I is a Single protein structure of sequence from Pyrococcus horikoshii. Full crystallographic information is available from OCA.
Reference
Crystal structure of a hyperthermophilic archaeal acylphosphatase from Pyrococcus horikoshii--structural insights into enzymatic catalysis, thermostability, and dimerization., Cheung YY, Lam SY, Chu WK, Allen MD, Bycroft M, Wong KB, Biochemistry. 2005 Mar 29;44(12):4601-11. PMID:15779887
Page seeded by OCA on Sun Jul 27 21:50:11 2008
