title: Ultrahigh-resolution optical trap with single-fluorophore sensitivity.
abstract: We present a single-molecule instrument that combines a time-shared ultrahigh-resolution dual optical trap interlaced with a confocal fluorescence microscope. In a demonstration experiment, we observed individual single fluorophore-labeled DNA oligonucleotides to bind and unbind complementary DNA suspended between two trapped beads. Simultaneous with the single-fluorophore detection, we clearly observed coincident angstrom-scale changes in tether extension. Fluorescence readout allowed us to determine the duplex melting rate as a function of force. The new instrument will enable the simultaneous measurement of angstrom-scale mechanical motion of individual DNA-binding proteins (for example, single-base-pair stepping of DNA translocases) along with the detection of properties of fluorescently labeled protein (for example, internal configuration).
authors.affiliation: Department of Physics and Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Comstock
authors.forename: Taekjip
authors.initials: T
authors.lastname: Ha
authors.forename: Yann R
authors.initials: YR
authors.lastname: Chemla
mesh_terms: D000818:Animals; D004247:DNA / Q000737:chemistry*; D018076:DNA, Complementary / Q000737:chemistry*; D005456:Fluorescent Dyes; D008846:Micromanipulation; D018613:Microscopy, Confocal / Q000379:methods; D008856:Microscopy, Fluorescence; D055096:Optical Devices
chemical_list: D018076:DNA, Complementary; D005456:Fluorescent Dyes; D004247:DNA