Linked Life Data

8457567

Source:http://linkedlifedata.com/resource/pubmed/id/8457567

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
12
pubmed:dateCreated
1993-4-27
pubmed:abstractText
The very strong helical propensity of peptides rich in alpha-aminoisobutyric acid (Aib) has enabled the design of a set of helices containing as guest amino acids one fluorescent chromophore, beta-(1'-naphthyl)-L-alanine, and one heavy atom perturber, p-bromo-L-phenylalanine. The fluorescence of the chromophoric residue was monitored in this set to explore heavy atom induced enhanced intersystem crossing as a potentially useful tool for exploring remote electronic interactions in biomolecules. The peptides in this set were sequence isomers of each other and were designed such that the chromophore and the perturber were separated by two, one, or zero Aib residues. The respective distances between the aromatic side chains are then modulated by the twist of the helix. All peptides showed steady-state fluorescence quenching, and on the basis of further time-resolved triplet-triplet absorption experiments, two mechanisms for the heavy atom induced fluorescence quenching were established: (i) a weak and nominally spin-forbidden singlet-triplet energy transfer and (ii) the remote heavy atom effect (RHAE) on the intersystem crossing within the fluorophore. Both the rate of singlet-triplet energy-transfer and the RHAE are at their maxima in the peptide with the largest sequence separation but the smallest direct distance between the chromophore and the perturber. Thus neither quenching mechanism is controlled by the length of the intervening covalent pathway. Subtle factors arising from the structure of the intervening peptide backbone apparently contribute to the RHAE for the peptides with shorter sequence separation. Because the sensitivity to the remote heavy atom is a measure of electronic delocalization, this result may have significance for the understanding of the role of helices in biological electron-transfer interactions.
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
30
pubmed:volume
32
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
3067-76
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1993
pubmed:articleTitle
Fluorescence quenching in a strongly helical peptide series: the role of noncovalent pathways in modulating electronic interactions.
pubmed:affiliation
Baker Laboratory, Department of Chemistry, Cornell University, Ithaca, New York 14853.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, U.S. Gov't, Non-P.H.S., Research Support, Non-U.S. Gov't