期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1982
卷号：79
期号：15
页码：4560-4564
DOI：10.1073/pnas.79.15.4560
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Negative supercoiling of plasmid DNAs containing 24--42 base pairs of alternating d(pCpG) inserts is shown to cause the flipping of the helical hand of the inserts from right to left under physiological conditions. For a negatively supercoiled DNA with a fixed linking number, this flipping reduces its superhelicity and, therefore, is accompanied by a shift of its electrophoretic mobility in agarose gel. Quantitation of the mobility shifts indicates that essentially the whole stretch of contiguous alternating d(pCpG) flips to the left-handed helical form when the negative superhelical density (specific linking difference) is greatest than or equal to 0.03.
