Nucleic Acids Research, Vol 26, Issue 18 4173-4177, Copyright © 1998 by Oxford University Press
P Aich, S Ritchie, K Bonham and JS Lee
The thermodynamic and kinetic parameters of triplex formation between four
purine-rich oligonucleotides and a 22 bp pyrimidine. purine tract in the
promoter region of the c-src gene were determined by fluorescence
polarization studies. Three of these four oligonucleotides were 11 nt in
length, corresponding to the left, central or right portion of the tract,
while the fourth was a 22mer covering the whole tract. Binding constants (
Ka) were measured as a function of Mg2+ concentration (0-10 mM) and
temperature (0-41 degrees C). In 10 mM Mg2+, K a for the left, central and
right 11mers were 0.26, 0.75 and 1.4 x 10(8)/M, respectively, while for the
22mer the value was 1.8 x 10(8)/M at 22 degrees C. Under the same
conditions, Ka was estimated by an electrophoretic band shift technique.
The agreement between the two methods was acceptable for the 22mer but not
for the 11mers. Kinetic measurements demonstrated that the rate of
dissociation of the 22mer from the triplex was significantly slower than
that of the 11mers, providing an explanation for the observed discrepancy.
The entropy and enthalpy of triplex formation were calculated from van't
Hoff plots. In all cases the entropy was favourable, especially for the
22mer and for the 11mer with the lowest guanine content. The enthalpy was
unfavourable for the 22mer and most favourable for the 11mer with the
highest guanine content. These results provide a thermodynamic explanation
for length and sequence effects on the formation of
purine.pyrimidine.purine triplexes.
ARTICLES
Thermodynamic and kinetic studies of the formation of triple helices between purine-rich deoxyribo-oligonucleotides and the promoter region of the human c-src proto-oncogene
Department of Biochemistry, University of Saskatchewan, 107 Wiggins Road, Saskatoon, SK S7N 5E5, Canada and Saskatoon Cancer Research Unit, 20 Campus Drive, Saskatoon, SK S7N 5E5, Canada.
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  F. Nagatsugi, S. Sasaki, P. S. Miller, and M. M. Seidman Site-specific mutagenesis by triple helix-forming oligonucleotides containing a reactive nucleoside analog Nucleic Acids Res., March 15, 2003; 31(6): e31 - e31. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. A. J. Darby, M. Sollogoub, C. McKeen, L. Brown, A. Risitano, N. Brown, C. Barton, T. Brown, and K. R. Fox High throughput measurement of duplex, triplex and quadruplex melting curves using molecular beacons and a LightCycler Nucleic Acids Res., May 1, 2002; 30(9): e39 - e39. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. Aich, T. J. Thomas, and J. S. Lee The role of polyamines, Na+ and K+ in the formation of triple helices between purine oligonucleotides and the promoter region of the human c-src proto-oncogene Nucleic Acids Res., June 15, 2000; 28(12): 2307 - 2310. [Abstract] [Full Text] [PDF]
|
|