Magnetic tweezers measurement of single molecule torque.
Torsional stress in linear biopolymers such as DNA and chromatin has important consequences for nanoscale biological processes. We have developed a new method to directly measure torque on single molecules. Using a cylindrical magnet, we manipulate a novel probe consisting of a nanorod with a 0.1 microm ferromagnetic segment coupled to a magnetic bead. We achieve controlled introduction of turns into the molecule and precise measurement of torque and molecule extension as a function of the number of turns at low pulling force. We show torque measurement of single DNA molecules and demonstrate for the first time measurements of single chromatin fibers.
Celedon
Alfredo
A
Department of Mechanical Engineering, Howard Hughes Medical Institute Graduate Training Program and Institute for NanoBioTechnology, Johns Hopkins University, Baltimore Maryland 21218, USA.
Nodelman
Ilana M
IM
Wildt
Bridget
B
Dewan
Rohit
R
Searson
Peter
P
Wirtz
Denis
D
Bowman
Gregory D
GD
Sun
Sean X
SX
D001704:Biopolymers; D002843:Chromatin / Q000737:chemistry; D004247:DNA / Q000737:chemistry; D008280:Magnetics
D001704:Biopolymers; D002843:Chromatin; D004247:DNA