Linked Life Data

2538447

Source:http://linkedlifedata.com/resource/pubmed/id/2538447

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
8
pubmed:dateCreated
1989-4-25
pubmed:abstractText
A ubiquinone derivative, 3-chloro-5-hydroxyl-2-methyl-6-decyl- 1,4-benzoquinone (3-CHMDB), which shows different effects on the mitochondrial cytochrome b-c1 complex and chloroplast cytochrome b6-f complex, has been synthesized and characterized. When the cytochrome b-c1 complex is treated with varying concentrations of 3-CHMDB and assayed at constant substrate (Q2H2) concentration, a 50% inhibition is observed when 2 mol of 3-CHMDB per mol of enzyme are used. The degree of inhibition is dependent on the substrate concentration. When ubiquinol-cytochrome c reductase is treated with 2 mol of 3-CHMDB per mol of enzyme, less inhibition is observed with a lower substrate concentration, suggesting the possible existence of two forms of reductases: one with a high affinity for ubiquinone and another with a low affinity. 2-Chloro-5-hydroxyl-3-methyl-6-decyl-1,4-benzoquinone (2-CHMDB), an isomer of 3-CHMDB, shows much less inhibition of the mitochondrial cytochrome b-c1 complex, suggesting that the quinone binding site in this complex is highly specific. In contrast to the inhibition observed with the cytochrome b-c1 complex, 3-CHMDB causes no inhibition of the plastoquinol-plastocyanin reductase activity of chloroplast cytochrome b6-f complex, regardless of whether plastoquinol-2 or ubiquinol-2 is used as substrate. 3-CHMDB restores the dibromothymoquinone-altered EPR spectra of iron-sulfur protein in both complexes. In the case of the cytochrome b6-f complex, 3-CHMDB also partially restores the dibromothymoquinone-inhibited activity. Reduced form 3- or 2-CHMDB is oxidizable by the cytochrome b6-f complex, but not by the cytochrome b-c1 complex. These results suggest that the quinol oxidizing sites in the cytochrome b6-f complex may differ from those in the mitochondrial cytochrome b-c1 complex.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Mar
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
15
pubmed:volume
264
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
4506-12
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed-meshheading:2538447-Binding Sites, pubmed-meshheading:2538447-Chemical Phenomena, pubmed-meshheading:2538447-Chemistry, pubmed-meshheading:2538447-Chloroplasts, pubmed-meshheading:2538447-Cytochrome b Group, pubmed-meshheading:2538447-Cytochrome b6f Complex, pubmed-meshheading:2538447-Electron Spin Resonance Spectroscopy, pubmed-meshheading:2538447-Electron Transport Complex III, pubmed-meshheading:2538447-Hydrogen-Ion Concentration, pubmed-meshheading:2538447-Iron-Sulfur Proteins, pubmed-meshheading:2538447-Isomerism, pubmed-meshheading:2538447-Magnetic Resonance Spectroscopy, pubmed-meshheading:2538447-Membrane Lipids, pubmed-meshheading:2538447-Mitochondria, pubmed-meshheading:2538447-Oxidation-Reduction, pubmed-meshheading:2538447-Plants, pubmed-meshheading:2538447-Rhodobacter sphaeroides, pubmed-meshheading:2538447-Spectrophotometry, pubmed-meshheading:2538447-Structure-Activity Relationship, pubmed-meshheading:2538447-Ubiquinone
pubmed:year
1989
pubmed:articleTitle
A ubiquinone derivative that inhibits mitochondrial cytochrome b-c1 complex but not chloroplast cytochrome b6-f complex activity.
pubmed:affiliation
Department of Biochemistry, Oklahoma State University, Stillwater 74078.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, U.S. Gov't, P.H.S., Research Support, U.S. Gov't, Non-P.H.S.