Abstract
A micro-channel with laser trapping system was fabricated to measure DNA rewinding rates of the enzyme (HsKu70). The HsKu70 with EGFP (fluolescent protein) was prepared in Ecoli., and the EGFP-HsKu70 was purified after the incubation. The fusion protein EGFP-HsKu70 is necessary for the direct visualization of the enzyme motion. A streptavidin-coated fluorescent bead was attached to λ-DNA, to capture the bead-DNA complex by an optical trapping for the measurements. The DNA unwinding rate of the enzyme can be obtained by measuring the distance between the trapped fluorescent bead and EGFP-HsKu70.
