Linked Life Data

1731926

Source:http://linkedlifedata.com/resource/pubmed/id/1731926

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
1992-2-25
pubmed:abstractText
The mechanism of luminescence quenching by spin labels was investigated in aqueous solution by steady-state and time-resolved luminescence techniques. Water-soluble nitroxide radicals strongly quenched the luminescence emitted by Tb3+ chelates and by fluorescein, either free or conjugated to proteins. The following features of the quenching reaction were established: (I) the rate constant for quenching of triplet-state Tb3+ by nitroxides was about 4 orders of magnitude smaller (ca. 10(5) M-1 s-1) than those of the singlet-state probes; (II) the quenchers reduced the excited-state lifetime of both probes; (III) the rate constants for quenching of both probes were found to be apparently independent of the temperature (between 6 and 42 degrees C) and viscosity (up to 60 mPa.s) of the solutions; (IV) both singlet and triplet quenching rates were sensitive to solvent polarity; (V) there is a small but significant spectral overlap between the absorption band of weekly absorbing nitroxide radicals and the emission spectra of luminophores, the extent of which, however, does not correlate with the extent of quenching; (VI) the quenching rate declines sharply with an increasing luminophore to nitroxide distance. The distance dependence of the quenching rate showed a satisfactory fit to an exponential function. These findings indicate that the quenching reaction is dominated by an electron exchange between the excited singlet- or triplet-state luminophore and the nitroxide radical rather than controlled by diffusional properties of the reactants.(ABSTRACT TRUNCATED AT 250 WORDS)
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
28
pubmed:volume
31
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
703-11
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1992
pubmed:articleTitle
Luminescence quenching by nitroxide spin labels in aqueous solution: studies on the mechanism of quenching.
pubmed:affiliation
Department of Biology, Johns Hopkins University, Baltimore, Maryland 21218.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, U.S. Gov't, P.H.S.