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| - | [[Image:1aj8.gif|left|200px]] | + | {{Seed}} |
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| | {{STRUCTURE_1aj8| PDB=1aj8 | SCENE= }} | | {{STRUCTURE_1aj8| PDB=1aj8 | SCENE= }} |
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| - | '''CITRATE SYNTHASE FROM PYROCOCCUS FURIOSUS'''
| + | ===CITRATE SYNTHASE FROM PYROCOCCUS FURIOSUS=== |
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| - | ==Overview==
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| - | The crystal structure of the closed form of citrate synthase, with citrate and CoA bound, from the hyperthermophilic Archaeon Pyrococcus furiosus has been determined to 1.9 A. This has allowed direct structural comparisons between the same enzyme from organisms growing optimally at 37 degrees C (pig), 55 degrees C (Thermoplasma acidophilum) and now 100 degrees C (Pyrococcus furiosus). The three enzymes are homodimers and share a similar overall fold, with the dimer interface comprising primarily an eight alpha-helical sandwich of four antiparallel pairs of helices. The active sites show similar modes of substrate binding; moreover, the structural equivalence of the amino acid residues implicated in catalysis implies that the mechanism proceeds via the same acid-base catalytic process. Given the overall structural and mechanistic similarities, it has been possible to make detailed structural comparisons between the three citrate synthases, and a number of differences can be identified in passing from the mesophilic to thermophilic to hyperthermophilic citrate synthases. The most significant of these are an increased compactness of the enzyme, a more intimate association of the subunits, an increase in intersubunit ion pairs, and a reduction in thermolabile residues. Compactness is achieved by the shortening of a number of loops, an increase in the number of atoms buried from solvent, an optimized packing of side chains in the interior, and an absence of cavities. The intimate subunit association in the dimeric P. furiosus enzyme is achieved by greater complementarity of the monomers and by the C-terminal region of each monomer folding over the surface of the other monomer, in contrast to the pig enzyme where the C-terminus has a very different fold. The increased number of intersubunit ion pairs is accompanied by an increase in the number involved in networks. Interestingly, all loop regions in the P. furiosus enzyme either are shorter or contain additional ion pairs compared with the pig enzyme. The possible relevance of these structural features to enzyme hyperthermostability is discussed. | + | The line below this paragraph, {{ABSTRACT_PUBMED_9254593}}, adds the Publication Abstract to the page |
| | + | (as it appears on PubMed at http://www.pubmed.gov), where 9254593 is the PubMed ID number. |
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| | + | {{ABSTRACT_PUBMED_9254593}} |
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| | ==About this Structure== | | ==About this Structure== |
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| | [[Category: Hyperthermostable]] | | [[Category: Hyperthermostable]] |
| | [[Category: Lyase]] | | [[Category: Lyase]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 10:20:34 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jun 30 16:58:09 2008'' |
Revision as of 13:58, 30 June 2008
Template:STRUCTURE 1aj8
CITRATE SYNTHASE FROM PYROCOCCUS FURIOSUS
Template:ABSTRACT PUBMED 9254593
About this Structure
1AJ8 is a Single protein structure of sequence from Pyrococcus furiosus. Full crystallographic information is available from OCA.
Reference
The crystal structure of citrate synthase from the hyperthermophilic archaeon pyrococcus furiosus at 1.9 A resolution,., Russell RJ, Ferguson JM, Hough DW, Danson MJ, Taylor GL, Biochemistry. 1997 Aug 19;36(33):9983-94. PMID:9254593
Page seeded by OCA on Mon Jun 30 16:58:09 2008
