Surface plasmon resonance analysis of topoisomerase I-DNA binding: effect of Mg2+ and DNA sequence.

Surface plasmon resonance detection was used to characterize interactions of human topoisomerase I and DNA. The disassociation of topoisomerase I and DNA is characterized by two rate constants. This suggests two parallel but independent pathways of release. DNA association appears to be complex. Mg2+ was found to increase both disassociation rate constants and may have a detectable effect on topoisomerase I-DNA association. DNA base content did not affect disassociation rate constants or the rate of association.