Linked Life Data

7547925

Source:http://linkedlifedata.com/resource/pubmed/id/7547925

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
37
pubmed:dateCreated
1995-10-30
pubmed:abstractText
Ion channels formed by the peptide gramicidin A in planar lipid membranes have been reported to react very sensitively upon irradiation of the membrane by ionizing radiation (radiolysis), by UV light (photolysis), or by visible light in the presence of appropriate photosensitizers (photodynamic inactivation). In all three cases the effect is due to the presence of the four tryptophan residues of the pentadecapeptide. Modifications of these amino acids--due to an interaction with free radicals formed upon water radiolysis or due to light absorption--have been found to reduce the membrane conductance by many orders of magnitude. The present study was intended to correlate functional changes, observed at the level of single ion channels, with changes of the molecular structure identified by mass spectrometry. About 98% of the inactivated channels showed a single-channel conductance of virtually zero, while about 2% of the channels present before irradiation are converted to a state of reduced conductance (and reduced lifetime). On the structural level, irradiation in the presence of the photosensitizer Rose Bengal was found to produce oxidation and fragmentation of the peptide at the positions of the tryptophan residues. Our results provide evidence that the main effect of radiolysis, or of photodynamic treatment, is the cleavage of the peptide backbone leading to immediate closure of an open ion channel.
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
19
pubmed:volume
34
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
11895-903
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1995
pubmed:articleTitle
Photodynamic and radiolytic inactivation of ion channels formed by gramicidin A: oxidation and fragmentation.
pubmed:affiliation
Department of Biology, University of Konstanz, Germany.
pubmed:publicationType
Journal Article, In Vitro, Research Support, Non-U.S. Gov't