Kinetics of conformational fluctuations in DNA hairpin-loops.
The kinetics of DNA hairpin-loop fluctuations has been investigated by using a combination of fluorescence energy transfer and fluorescence correlation spectroscopy. We measure the chemical rates and the activation energies associated with the opening and the closing of the hairpin for different sizes and sequences of the loop and for various salt concentrations. The rate of unzipping of the hairpin stem is essentially independent of the characteristics of the loop, whereas the rate of closing varies greatly with the loop length and sequence. The closing rate scales with the loop length, with an exponent 2.6 +/- 0.3. The closing rate is increased at higher salt concentrations. For hairpin closing, a loop of adenosine repeats leads to smaller rates and higher activation energies than a loop with thymine repeats.
Center for Studies in Physics and Biology, The Rockefeller University, 1230 York Avenue, New York NY 10021, USA.
G
G
Bonnet
O
O
Krichevsky
A
A
Libchaber
D004247:DNA / Q000737:chemistry*; D007700:Kinetics; D009690:Nucleic Acid Conformation; D009994:Osmolar Concentration; D012965:Sodium Chloride; D013050:Spectrometry, Fluorescence
D012965:Sodium Chloride; D004247:DNA