Entropic boundary effects on the elasticity of short DNA molecules.
We have measured the entropic elasticity of double-stranded-DNA molecules ranging from 247 to 1298 bp in length using axial force-clamp optical tweezers. We show that entropic end effects and excluded-volume forces from surface attachments become significant for such short molecules. The effective persistence length of the shortest molecules decreases by a factor of 2 compared to the established value for long molecules, and excluded-volume forces extend the molecules to about one third of their nominal contour length. We interpret these results in the framework of an inextensible semiflexible rod model.
Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA.
Yih-Fan
YF
Chen
David P
DP
Wilson
Krishnan
K
Raghunathan
Jens-Christian
JC
Meiners
D004247:DNA / Q000737:chemistry*; D004548:Elasticity; D019277:Entropy; D052898:Optical Tweezers; D013499:Surface Properties
D004247:DNA