This supercoiled plasmid is a pUC19 derivative in which the 206 bp SphI-NarI fragment of pUC19 was replaced with a 245 bp SphI-AccI fragment upstream of the human adult beta-globin gene promoter. The 245 bp fragment contains a 54 bp alternating repeat of purine/pyrimidine sequence that constitutes a strong eukaryotic topoisomerase II cleavage site. Cleavages within the repeat are readily detected in the absence of topoisomerase II inhibitors such as m-AMSA or VM-26. The sequence of the plasmid is given in Table 2 of Spitzner et al (reference below).
