The Effect of Dimethyl Sulfoxide on Supercoiled DNA Relaxation Catalyzed by Type I Topoisomerases

Figure 3

DMSO reduce the inhibition induced by dsODN in EcTopo I catalyzed relaxation. (a) Electrophoretic analysis of EcTopo I catalyzed relaxation inhibition assay in the presence or absence of DMSO. Lane 1: untreated pBR322 plasmid. Lanes 2–6: the mixtures containing EcTopo I (Lane 2); EcTopo I and ssODN (Lane 3); EcTopo I, ssODN, and 20% DMSO (Lane 4); EcTopo I and dsODN (Lane 5); and EcTopo I, dsODN, and 20% DMSO (Lane 6) were preincubated at 37°C for 3 minutes. pBR322 substrate was added to the resulting solutions and incubated at 37°C for 30 minutes. (b) Electrophoretic analysis of CtTopo I catalyzed relaxation inhibition assay in the presence or absence of DMSO. The experiments were conducted in the same ways as shown in (a) except that EcTopo I was replaced by CtTopo I.

(a)

(b)