Linked Life Data

7619828

Source:http://linkedlifedata.com/resource/pubmed/id/7619828

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
28
pubmed:dateCreated
1995-8-30
pubmed:abstractText
DNA motions consist of several components which couple, making their investigation difficult. This study describes an approach for obtaining dynamical information by EPR when spin-labeled nucleic acids are examined. The analysis is accomplished by implementing two motional models. The first model (i.e., dynamic cylinder model) views the spin-labeled helix as a diffusing cylinder containing internal dynamics which are characterized by an order parameter. The second model (i.e., base disk model) provides correlation times describing the diffusion of the spin-labeled base. In each model, the nitroxide motion consists of both global and internal contributions. Dynamic cylinder and base disk simulations of four duplexes containing nitroxides attached to thymidine by a two-atom tether (DUMTA)-(dT)7DUMTA-(dT)7.(dA)15, [(dT)7DUMTA(dT)7]2.(dA)30, [(dT)7DUMTA(dT)7]3.(dA)45, and [(dT)7DUMTA(dT)7]m.-(dA)n--demonstrate the useful application of this approach. From dynamic cylinder simulations, the order parameter for internal motions is found to be independent of the helix length (S = 0.32 +/- 0.01). Previous base disk simulations of a DNA 26mer and polymer labeled with a five-atom-tethered nitroxide seemed to indicate that tau perpendicular was only sensitive to internal dynamics. Results from base disk simulations of DUMTA-labeled DNA indicate that the perpendicular component of the base disk correlation time (tau perpendicular = 1.4-6.2 ns) is sensitive to global dynamics. Thus, tau perpendicular is a quantitative indicator of both internal and global dynamics. Comparison of the two models reveals that tau perpendicular infinity S2 tau rb, where tau rb represents the rigid-body diffusion of the DNA helix. This relationship between S and tau perpendicular provides a framework for studying conformational changes and size-dependent phenomena in spin-labeled nucleic acids. Application of the dynamic cylinder model to a B-Z transition generates distinct values of S for each of the conformations, indicating that Z-DNA is more rigid than B-DNA.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jul
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
18
pubmed:volume
34
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
9265-76
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1995
pubmed:articleTitle
Detection of internal and overall dynamics of a two-atom-tethered spin-labeled DNA.
pubmed:affiliation
Department of Chemistry, University of Cincinnati, Ohio 45221, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.