Biopolymers and cell. 1993. Volume 9. № 6. 52 - 59

SOLOVYAN V. T., ANDREYEV I. O.

Fractionation of Eukaryotic DNA by Pulsed Field Gel Electrophoresis. The Peculiarities of Topoisomerase / DNA Complex Behaviour in Isolated Nuclei

Summary

    The properties of topoisomerase II/DNA complex in nuclear prepara¬tions have been investigated. It has been shown that topoll/nuclear DNA complex functiones unitypically both in Mg²⁺- and in Ca²⁺-containing media. Unlike to the in vitro assay the treatment of topoll/nuclear DNA complex with EDTA resulted in increase of nuclear DNA cleavage rather than its rejoining. The nuclear topoII/DNA complex treated with SDS was found to acquire the capacity to subsequent SDS-independent nuclear DNA cleavage. The salient features of topoisomerase II/nuclear DNA complex are supposed to be due to the topoII enzyme involvement in higher level's chromatin compactization leading to the initial stabilization of topoll/nuclear DNA complex in vivo conditions. The availability in cells the different topoII/DNA complex variants of possible physiological value has been proposed.