Long-time stretched exponential kinetics in single DNA duplex dissociation
Paul L. Biancaniello 1, Anthony J. Kim 1 and John C. Crocker 1*
1 University of Pennsylvania
* To whom correspondence should be addressed. E-mail: jcrocker{at}seas.upenn.edu.
Submitted on March 7, 2007
Revised on July 17, 2007
Accepted on 13 September 2007
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Abstract |
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We probe DNA hybridization kinetics by measuring the lifetime distribution of single 16-bp duplexes under thermal dissociation. Our unique approach, based on two DNA-coated microspheres in an extended optical tweezer, allows the study of single duplex DNA molecules under negligible molecular tension. In contrast to earlier experiments, we find a stretched exponential lifetime distribution, which is likely due to dissociation proceeding via a number of competing pathways between highly force sensitive intermediate states. Similar measurements of microspheres linked by multiple DNA bridges find they have unexpected short bound lifetimes, also consistent with force sensitivity.
Key Words:
DNA hybridization, binding kinetics, microspheres, non-exponential kinetics, optical tweezer, single-molecule biophysics
