Linked Life Data

9748325

Source:http://linkedlifedata.com/resource/pubmed/id/9748325

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
38
pubmed:dateCreated
1998-10-22
pubmed:abstractText
Of several furanocoumarins [5-methoxypsoralen (5-MOP), 8-methoxypsoralen (8-MOP), 5-hydroxypsoralen (5-OH-P), 8-hydroxypsoralen (8-OH-P), 4',5'-dihydro-8-MOP (DH-8-MOP), and psoralen (P)] tested as mechanism-based inactivators (MBIs) of purified reconstituted cytochrome P450 (P450) 2B1, 8-MOP was found to be the most potent (KI, kinact, and partition ratio of 2.9 microM, 0.34 min-1, and 1.3, respectively). The inactivation was not prevented by reactive oxygen species scavengers or nucleophilic trapping agents and proceeded with a decrease in P450 spectral content. Liquid chromatography (LC) separation of the reconstituted enzyme mixture, followed by liquid scintillation counting, indicated that [14C]-8-MOP binding was specific to the apoprotein of P450 2B1 with a binding stoichiometry of 0.7:1. The major metabolites formed by P450 2B1 from the furanocoumarins that were MBIs were characterized by LC electrospray ionization tandem mass spectrometry (ESI-MS/MS) as dihydro diols. Results from H218O incorporation experiments supported initial oxidation of 8-MOP and P to an epoxide which can react with some nucleophilic active site residue and inactivate the enzyme or partition to a dihydro diol metabolite by hydrolytic ring opening. On the other hand, 5-MOP was converted to an epoxide or gamma-keto enal intermediate prior to inactivation or dihydro diol formation. Comparison of the ESI mass spectra of P450 2B1 and furanocoumarin exposed P450 2B1, indicated a mass difference consistent with the covalent addition of a furanoepoxide to P450 2B1.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
22
pubmed:volume
37
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
13184-93
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1998
pubmed:articleTitle
Mechanism-based inactivation of cytochrome P450 2B1 by 8-methoxypsoralen and several other furanocoumarins.
pubmed:affiliation
Department of Medicinal Chemistry, University of Washington, Seattle 98195, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't