C. Hoyer et al., LASER MANIPULATION AND UV INDUCED SINGLE-MOLECULE REACTIONS OF INDIVIDUAL DNA-MOLECULES, Journal of biotechnology, 52(2), 1996, pp. 65-73
Individual fluorescently labelled DNA molecules were bound to microbea
ds. Controlled handling was. possible using a double beam optical trap
and by electric fields but without the additional help of viscous dra
g. Trapping and stretching of single molecules is shown under conditio
ns where enzymes are active. After trapping the bead with optical twee
zers and stretching the DNA in an electric field, an enzyme reaction w
as started by UV photolysis of a caged compound for Mg2+ ions. The res
triction endonuclease, ApaI cut the DNA molecule into two fragments. W
hile one remained bound to the bead and fixed in the laser focus, the
other fragment was dragged away towards the positive electrode. In con
clusion, a single molecule--enzyme reaction recorded with a single pho
ton counting camera and an image processing system is shown in a light
microscope. (C) 1996 Elsevier Science B.V. All rights reserved.