Linked Life Data

7532020

Source:http://linkedlifedata.com/resource/pubmed/id/7532020

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
5
pubmed:dateCreated
1995-3-22
pubmed:abstractText
A nitroxide spin label attached to the C-terminus of the channel forming peptide alamethicin produces an enhancement of the nuclear spin-lattice relaxation rates of peptide protons as a result of both intermolecular and intramolecular magnetic dipole-dipole interactions. The intermolecular contribution provides evidence that alamethicin monomers collide preferentially in a C-terminal-to-N-terminal configuration in methanol. From the intramolecular paramagnetic enhancement of nuclear spin-lattice relaxation times, effective distances between the unpaired electron on the nitroxide at the C-terminus of alamethicin and protons along the peptide backbone were calculated. These distances are much shorter than distances based on the reported crystal structure of alamethicin, and cannot be accounted for by motion in the bonds that attach the nitroxide to the peptide. In addition, the differences between distances deduced from the nuclear spin relaxation and the distances seen in the crystal structure increase toward the N-terminal end of the peptide. The simplest explanation for these data is that the alamethicin backbone suffers large structural fluctuations that yield shorter effective distances between the C-terminus and positions along the backbone. This finding can be interpreted in terms of a molecular mechanism for the voltage-gating of the alamethicin channel. When the distances between a paramagnetic center and a nucleus fluctuate, paramagnetic enhancements are expected to yield distances that are weighted by r-6, and distances calculated using the Solomon-Bloembergen equations may more nearly represent a distance of closest approach than a time average distance. Therefore, the use of paramagnetic centers such as spin labels or metal ions with long electron T1 values provides a distance measurement that reflects a dynamically averaged structure where the averaging process heavily weights short distances. The results of such measurements, when combined with other structural information, may provide particularly clear evidence for the magnitude of structural fluctuations involving distances greater than 10 A.
pubmed:grant
pubmed:commentsCorrections
http://linkedlifedata.com/resource/pubmed/commentcorrection/7532020-1314904, http://linkedlifedata.com/resource/pubmed/commentcorrection/7532020-1554700, http://linkedlifedata.com/resource/pubmed/commentcorrection/7532020-1606136, http://linkedlifedata.com/resource/pubmed/commentcorrection/7532020-1606151, http://linkedlifedata.com/resource/pubmed/commentcorrection/7532020-1717016, http://linkedlifedata.com/resource/pubmed/commentcorrection/7532020-2081267, http://linkedlifedata.com/resource/pubmed/commentcorrection/7532020-2436657, http://linkedlifedata.com/resource/pubmed/commentcorrection/7532020-6292726, http://linkedlifedata.com/resource/pubmed/commentcorrection/7532020-6302469, http://linkedlifedata.com/resource/pubmed/commentcorrection/7532020-7511413, http://linkedlifedata.com/resource/pubmed/commentcorrection/7532020-7522664
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Nov
pubmed:issn
0006-3495
pubmed:author
pubmed:issnType
Print
pubmed:volume
67
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1861-6
pubmed:dateRevised
2009-11-18
pubmed:meshHeading
pubmed:year
1994
pubmed:articleTitle
Molecular flexibility demonstrated by paramagnetic enhancements of nuclear relaxation. Application to alamethicin: a voltage-gated peptide channel.
pubmed:affiliation
Department of Chemistry, University of Virginia, Charlottesville 22901.
pubmed:publicationType
Journal Article, In Vitro, Research Support, U.S. Gov't, P.H.S.