Source:http://linkedlifedata.com/resource/pubmed/id/21504201
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rdf:type | |
lifeskim:mentions | |
pubmed:issue |
18
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pubmed:dateCreated |
2011-5-4
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pubmed:abstractText |
The isochorismate-pyruvate lyase from Pseudomonas aeruginosa (PchB) catalyzes two pericyclic reactions, demonstrating the eponymous activity and also chorismate mutase activity. The thermodynamic parameters for these enzyme-catalyzed activities, as well as the uncatalyzed isochorismate decomposition, are reported from temperature dependence of k(cat) and k(uncat) data. The entropic effects do not contribute to enzyme catalysis as expected from previously reported chorismate mutase data. Indeed, an entropic penalty for the enzyme-catalyzed mutase reaction (?S(++) = -12.1 ± 0.6 cal/(mol K)) is comparable to that of the previously reported uncatalyzed reaction, whereas that of the enzyme-catalyzed lyase reaction (?S(++) = -24.3 ± 0.2 cal/(mol K)) is larger than that of the uncatalyzed lyase reaction (-15.77 ± 0.02 cal/(mol K)) documented here. With the assumption that chemistry is rate-limiting, we propose that a reactive substrate conformation is formed upon loop closure of the active site and that ordering of the loop contributes to the entropic penalty for converting the enzyme substrate complex to the transition state.
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pubmed:grant | |
pubmed:language |
eng
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pubmed:journal | |
pubmed:citationSubset |
IM
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pubmed:chemical |
http://linkedlifedata.com/resource/pubmed/chemical/Bacterial Proteins,
http://linkedlifedata.com/resource/pubmed/chemical/Carbon-Oxygen Lyases,
http://linkedlifedata.com/resource/pubmed/chemical/Chorismate Mutase,
http://linkedlifedata.com/resource/pubmed/chemical/Chorismic Acid,
http://linkedlifedata.com/resource/pubmed/chemical/isochorismic acid,
http://linkedlifedata.com/resource/pubmed/chemical/pchB protein, Pseudomonas aeruginosa
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pubmed:status |
MEDLINE
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pubmed:month |
May
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pubmed:issn |
1520-5126
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pubmed:author | |
pubmed:copyrightInfo |
© 2011 American Chemical Society
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pubmed:issnType |
Electronic
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pubmed:day |
11
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pubmed:volume |
133
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
7229-33
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pubmed:dateRevised |
2011-9-26
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pubmed:meshHeading |
pubmed-meshheading:21504201-Bacterial Proteins,
pubmed-meshheading:21504201-Carbon-Oxygen Lyases,
pubmed-meshheading:21504201-Catalysis,
pubmed-meshheading:21504201-Catalytic Domain,
pubmed-meshheading:21504201-Chorismate Mutase,
pubmed-meshheading:21504201-Chorismic Acid,
pubmed-meshheading:21504201-Entropy,
pubmed-meshheading:21504201-Pseudomonas aeruginosa,
pubmed-meshheading:21504201-Temperature
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pubmed:year |
2011
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pubmed:articleTitle |
Entropic and enthalpic components of catalysis in the mutase and lyase activities of Pseudomonas aeruginosa PchB.
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pubmed:affiliation |
Molecular Biosciences, University of Kansas, Lawrence, Kansas 66045, USA.
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pubmed:publicationType |
Journal Article,
Research Support, Non-U.S. Gov't,
Research Support, N.I.H., Extramural
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