Linked Life Data

10079091

Source:http://linkedlifedata.com/resource/pubmed/id/10079091

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
11
pubmed:dateCreated
1999-4-15
pubmed:abstractText
Diphenylamine (DPA), a known inhibitor of polyene and isoprene biosynthesis, is shown to inhibit flash-activatable electron transfer in photosynthetic membranes of Rhodobacter capsulatus. DPA is specific to the QO site of ubihydroquinone:cytochrome c oxidoreductase, where it inhibits not only reduction of the [2Fe-2S]2+ cluster in the FeS subunit and subsequent cytochrome c reduction but also heme bL reduction in the cytochrome b subunit. In both cases, the kinetic inhibition constant (Ki) is 25 +/- 10 microM. A novel aspect of the mode of action of DPA is that complete inhibition is established without disturbing the interaction between the reduced [2Fe-2S]+ cluster and the QO site ubiquinone complement, as observed from the electron paramagnetic resonance (EPR) spectral line shape of the reduced [2Fe-2S] cluster, which remained characteristic of two ubiquinones being present. These observations imply that DPA is behaving as a noncompetitive inhibitor of the QO site. Nevertheless, at higher concentrations (>10 mM), DPA can interfere with the QO site ubiquinone occupancy, leading to a [2Fe-2S] cluster EPR spectrum characteristic of the presence of only one ubiquinone in the QO site. Evidently, DPA can displace the more weakly bound of the two ubiquinones in the site, but this is not requisite for its inhibiting action.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Mar
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
16
pubmed:volume
38
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
3440-6
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1999
pubmed:articleTitle
Ubiquinone binding capacity of the Rhodobacter capsulatus cytochrome bc1 complex: effect of diphenylamine, a weak binding QO site inhibitor.
pubmed:affiliation
Johnson Research Foundation, Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia 19104, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.