Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
26
pubmed:dateCreated
2009-6-30
pubmed:abstractText
Human reticulocyte 15-lipoxygenase-1 (15-hLO-1) and human platelet 12-lipoxygenase (12-hLO) have been implicated in a number of diseases, with differences in their relative activity potentially playing a central role. In this work, we characterize the catalytic mechanism of these two enzymes with arachidonic acid (AA) as the substrate. Using variable-temperature kinetic isotope effects (KIE) and solvent isotope effects (SIE), we demonstrate that both k(cat)/K(M) and k(cat) for 15-hLO-1 and 12-hLO involve multiple rate-limiting steps that include a solvent-dependent step and hydrogen atom abstraction. A relatively low k(cat)/K(M) KIE of 8 was determined for 15-hLO-1, which increases to 18 upon the addition of the allosteric effector molecule, 12-hydroxyeicosatetraenoic acid (12-HETE), indicating a tunneling mechanism. Furthermore, the addition of 12-HETE lowers the observed k(cat)/K(M) SIE from 2.2 to 1.4, indicating that the rate-limiting contribution from a solvent sensitive step in the reaction mechanism of 15-hLO-1 has decreased, with a concomitant increase in the C-H bond abstraction contribution. Finally, the allosteric binding of 12-HETE to 15-hLO-1 decreases the K(M)[O(2)] for AA to 15 microM but increases the K(M)[O(2)] for linoleic acid (LA) to 22 microM, such that the k(cat)/K(M)[O(2)] values become similar for both substrates (approximately 0.3 s(-1) microM(-1)). Considering that the oxygen concentration in cancerous tissue can be less than 5 microM, this result may have cellular implications with respect to the substrate specificity of 15-hLO-1.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
http://linkedlifedata.com/resource/pubmed/chemical/12-HPETE, http://linkedlifedata.com/resource/pubmed/chemical/12-Hydroxy-5,8,10,14-eicosatetraenoi..., http://linkedlifedata.com/resource/pubmed/chemical/13-hydroperoxy-9,11-octadecadienoic..., http://linkedlifedata.com/resource/pubmed/chemical/13-hydroxy-9,11-octadecadienoic acid, http://linkedlifedata.com/resource/pubmed/chemical/15-hydroperoxy-5,8,11,13-eicosatetra..., http://linkedlifedata.com/resource/pubmed/chemical/ALOX12 protein, human, http://linkedlifedata.com/resource/pubmed/chemical/ALOX15 protein, human, http://linkedlifedata.com/resource/pubmed/chemical/Arachidonate 12-Lipoxygenase, http://linkedlifedata.com/resource/pubmed/chemical/Arachidonate 15-Lipoxygenase, http://linkedlifedata.com/resource/pubmed/chemical/Arachidonic Acid, http://linkedlifedata.com/resource/pubmed/chemical/Carbon Isotopes, http://linkedlifedata.com/resource/pubmed/chemical/Leukotrienes, http://linkedlifedata.com/resource/pubmed/chemical/Linoleic Acid, http://linkedlifedata.com/resource/pubmed/chemical/Linoleic Acids, http://linkedlifedata.com/resource/pubmed/chemical/Lipid Peroxides, http://linkedlifedata.com/resource/pubmed/chemical/Oxygen, http://linkedlifedata.com/resource/pubmed/chemical/Recombinant Proteins, http://linkedlifedata.com/resource/pubmed/chemical/Solvents
pubmed:status
MEDLINE
pubmed:month
Jul
pubmed:issn
1520-4995
pubmed:author
pubmed:issnType
Electronic
pubmed:day
7
pubmed:volume
48
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
6259-67
pubmed:dateRevised
2011-9-26
pubmed:meshHeading
pubmed-meshheading:19469483-12-Hydroxy-5,8,10,14-eicosatetraenoic Acid, pubmed-meshheading:19469483-Allosteric Regulation, pubmed-meshheading:19469483-Arachidonate 12-Lipoxygenase, pubmed-meshheading:19469483-Arachidonate 15-Lipoxygenase, pubmed-meshheading:19469483-Arachidonic Acid, pubmed-meshheading:19469483-Biocatalysis, pubmed-meshheading:19469483-Blood Platelets, pubmed-meshheading:19469483-Carbon Isotopes, pubmed-meshheading:19469483-Humans, pubmed-meshheading:19469483-Kinetics, pubmed-meshheading:19469483-Leukotrienes, pubmed-meshheading:19469483-Linoleic Acid, pubmed-meshheading:19469483-Linoleic Acids, pubmed-meshheading:19469483-Lipid Peroxides, pubmed-meshheading:19469483-Models, Chemical, pubmed-meshheading:19469483-Oxygen, pubmed-meshheading:19469483-Recombinant Proteins, pubmed-meshheading:19469483-Reticulocytes, pubmed-meshheading:19469483-Solvents, pubmed-meshheading:19469483-Temperature
pubmed:year
2009
pubmed:articleTitle
Mechanistic investigations of human reticulocyte 15- and platelet 12-lipoxygenases with arachidonic acid.
pubmed:affiliation
Chemistry and Biochemistry Department, University of California, Santa Cruz, California 95064, USA.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't, Research Support, N.I.H., Extramural