Source:http://linkedlifedata.com/resource/pubmed/id/10092596
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rdf:type | |
lifeskim:mentions | |
pubmed:issue |
14
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pubmed:dateCreated |
1999-4-27
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pubmed:abstractText |
Prostaglandin H synthase (PGHS) is a self-activating and self-inactivating enzyme. Both the peroxidase and cyclooxygenase activities have a limited number of catalytic turnovers. Sequential stopped-flow measurements were used to analyze the kinetics of PGHS-1 peroxidase self-inactivation during reaction with several different hydroperoxides. The inactivation followed single exponential kinetics, with a first-order rate constant of 0.2-0.5 s-1 at 24 degrees C. This rate was independent of the peroxide species and concentration used, strongly suggesting that the self-inactivation process originates after formation of Compound I and probably with Intermediate II, which contains an oxyferryl heme and a tyrosyl radical. Kinetic scan and rapid scan experiments were used to monitor the heme changes during the inactivation process. The results from both experiments converged to a simple, linear, two-step mechanism in which Intermediate II is first converted in a faster step (0.5-2 s-1) to a new compound, Intermediate III, which undergoes a subsequent slower (0.01-0.05 s-1) transition to a terminal species. Rapid-quench and high pressure liquid chromatography analysis indicated that Intermediate III likely retains an intact heme group that is not covalently linked with the PGHS-1 protein.
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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/15-hydroperoxy-5,8,11,13-eicosatetra...,
http://linkedlifedata.com/resource/pubmed/chemical/Cyclooxygenase 1,
http://linkedlifedata.com/resource/pubmed/chemical/Isoenzymes,
http://linkedlifedata.com/resource/pubmed/chemical/Leukotrienes,
http://linkedlifedata.com/resource/pubmed/chemical/Lipid Peroxides,
http://linkedlifedata.com/resource/pubmed/chemical/Peroxidase,
http://linkedlifedata.com/resource/pubmed/chemical/Prostaglandin-Endoperoxide Synthases,
http://linkedlifedata.com/resource/pubmed/chemical/Prostaglandins G,
http://linkedlifedata.com/resource/pubmed/chemical/prostaglandin G2
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pubmed:status |
MEDLINE
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pubmed:month |
Apr
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pubmed:issn |
0021-9258
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pubmed:author | |
pubmed:issnType |
Print
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pubmed:day |
2
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pubmed:volume |
274
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
9231-7
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pubmed:dateRevised |
2007-11-14
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pubmed:meshHeading |
pubmed-meshheading:10092596-Animals,
pubmed-meshheading:10092596-Catalysis,
pubmed-meshheading:10092596-Chromatography, High Pressure Liquid,
pubmed-meshheading:10092596-Cyclooxygenase 1,
pubmed-meshheading:10092596-Isoenzymes,
pubmed-meshheading:10092596-Kinetics,
pubmed-meshheading:10092596-Leukotrienes,
pubmed-meshheading:10092596-Lipid Peroxides,
pubmed-meshheading:10092596-Peroxidase,
pubmed-meshheading:10092596-Prostaglandin-Endoperoxide Synthases,
pubmed-meshheading:10092596-Prostaglandins G,
pubmed-meshheading:10092596-Sheep
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pubmed:year |
1999
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pubmed:articleTitle |
A mechanistic study of self-inactivation of the peroxidase activity in prostaglandin H synthase-1.
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pubmed:affiliation |
Division of Hematology, Department of Internal Medicine, University of Texas Health Science Center, Houston, Texas 77030, USA.
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pubmed:publicationType |
Journal Article,
Research Support, U.S. Gov't, P.H.S.,
Research Support, Non-U.S. Gov't
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