Linked Life Data

15823053

Source:http://linkedlifedata.com/resource/pubmed/id/15823053

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
15
pubmed:dateCreated
2005-4-12
pubmed:abstractText
To gain new insights into the function of photosystem II (PSII) herbicides DCMU (a urea herbicide) and bromoxynil (a phenolic herbicide), we have studied their effects in a better understood system, the bacterial photosynthetic reaction center of the terbutryn-resistant mutant T4 of Blastochloris (Bl.) viridis. This mutant is uniquely sensitive to these herbicides. We have used redox potentiometry and time-resolved absorption spectroscopy in the nanosecond and microsecond time scale. At room temperature the P(+)(*)Q(A)(-)(*) charge recombination in the presence of bromoxynil was faster than in the presence of DCMU. Two phases of P(+)(*)Q(A)(-)(*) recombination were observed. In accordance with the literature, the two phases were attributed to two different populations of reaction centers. Although the herbicides did induce small differences in the activation barriers of the charge recombination reactions, these did not explain the large herbicide-induced differences in the kinetics at ambient temperature. Instead, these were attributed to a change in the relative amplitude of the phases, with the fast:slow ratio being approximately 3:1 with bromoxynil and approximately 1:2 with DCMU at 300 K. Redox titrations of Q(A) were performed with and without herbicides at pH 6.5. The E(m) was shifted by approximately -75 mV by bromoxynil and by approximately +55 mV by DCMU. As the titrations were done over a time range that is assumed to be much longer than that for the transition between the two different populations, the potentials measured are considered to be a weighted average of two potentials for Q(A). The influence of the herbicides can thus be considered to be on the equilibrium of the two reaction center forms. This may also be the case in photosystem II.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Apr
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
19
pubmed:volume
44
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
5931-9
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2005
pubmed:articleTitle
Herbicide-induced changes in charge recombination and redox potential of Q(A) in the T4 mutant of Blastochloris viridis.
pubmed:affiliation
Institut für Biologie II, Biochemie der Pflanzen, Universität Freiburg, Schänzlestrasse 1, 79104 Freiburg, Germany. fufezan@cea.fr
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't