Linked Life Data

1731941

Source:http://linkedlifedata.com/resource/pubmed/id/1731941

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
1992-2-25
pubmed:abstractText
The DNA oligonucleotide d(CGCG3GCG) can form either a Watson-Crick (WC) hairpin or a parallel-stranded quadruplex structure containing six G-quartet base pair assemblies. The exchange between these forms and single strands can be monitored using circular dichroism (CD). NMR results verified the assignment of specific CD bands to quadruplex and hairpin species, respectively. Cations stabilize the quadruplex in the order K+ greater than Ca2+ greater than Na+ greater than Mg2+ greater than Li+ and K+ greater than Rb+ greater than Cs+, indicating that K+ has an optimum ionic radius for complex formation and that ionic charge affects the extent of ion-induced stabilization. The quadruplex is stable in the presence of 40 mM K+ at micromolar DNA concentration and can be kinetically trapped as a metastable form when prepared at millimolar DNA concentration and then diluted into buffer containing 40 mM Na+. The concentration of K+ required to reverse the equilibrium from the hairpin to the quadruplex decreases sharply with increased DNA concentration. The quadruplex has an unusual pKa of ca. 6.8, indicating that C.C+ base pairs are probably forming. This system provides insights into some of the detailed structural characteristics of a ["G4-DNA".ion] complex and an experimental model for the recently proposed "sodium-potassium conformational switch" [Sen, D., & Gilbert, W. (1988) Nature 334, 364-366; Sen, D., & Gilbert, W. (1990) Nature 344, 410-414]. These results may help to explain the lack of cytidine residues in G-rich telomeric DNAs and suggest that methylation of GC-rich duplex DNAs in "GpC islands" may induce quadruplex formation within heterochromatin domains, resulting in reversible chromosomal condensation.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
28
pubmed:volume
31
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
833-41
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1992
pubmed:articleTitle
Cation-dependent transition between the quadruplex and Watson-Crick hairpin forms of d(CGCG3GCG).
pubmed:affiliation
Department of Biochemistry, North Carolina State University, Raleigh 27695.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't