Linked Life Data

10504228

Source:http://linkedlifedata.com/resource/pubmed/id/10504228

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
39
pubmed:dateCreated
1999-10-20
pubmed:abstractText
Reported here is the solution structure of the aminoacyl-DNA duplex (W-TGCGCAC)(2). This duplex forms a continuously pi-stacked helix consisting of both nucleobases and amino acid side chains. According to NMR and UV analyses, the duplex melts in a cooperative transition and with 1.3-1.8% greater hyperchromicity than the control duplex (TGCGCAC)(2). A van't Hoff analysis of UV melting points at different concentrations shows that the two tryptophan residues contribute 4.8 kcal/mol to the DeltaH degrees of complex formation at 10 mM salt concentration and less than 1 kcal/mol at 150 mM salt. The entropic cost for duplex association in the presence of the amino acid residues is 13 cal/molK greater than that for the control at 10 mM salt concentration, and 3 cal/molK lower than that of the control at 0.15 ionic strength. The conformation of W-TGCGCAC in duplex form, determined via restrained torsion angle molecular dynamics, shows an undisturbed B-form DNA duplex with dangling 3'-termini. The tryptophanyl residue at the 5'-terminus packs tightly against T2 and the proximal part of adenine, without engaging in hydrogen bonding. While not providing strong enthalpic net stabilization of the duplex, the tryptophan "cap" on the duplex does seem to reduce the fraying at the termini, indicating a subtle balance of entropic and enthalpic factors contributing to the molecular dynamics. The structure also shows that, at least in the present sequence context, stacking on the terminal base pair is more favorable than intercalation, probably because the enthalpic cost associated with breaking up the stacking between DNA base pairs cannot be paid for by favorable pi-stacking interactions with the indole ring of tryptophan. These results are of importance for understanding stacking interactions in protein-DNA complexes, particularly those in enzyme-substrate complexes involving exposed nucleobases.
pubmed:grant
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
28
pubmed:volume
38
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
12597-606
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1999
pubmed:articleTitle
Solution structure of the aminoacyl-capped oligodeoxyribonucleotide duplex (W-TGCGCAC)(2).
pubmed:affiliation
Department of Chemistry, Tufts University, 62 Talbot Avenue, Medford, Massachusetts 02155, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't