Nucleic Acids Research, 1983, Vol. 11, No. 23 8421-8429
© 1983
CHEMISTRY |
Stabilization of (dG-dC)n.(dG-dC)n in the Z conformation by a crosslinking reaction
Department of Microbiology, Cancer Center/Institute of Cancer Research, Columbia University New York, NY 10032, USA
Received September 26, 1983. Accepted October 21, 1983.
(dG-dC)n.(dG-dC) was converted to the Z conformer by heating in the presence of Mnn++. Reaction of this preparation with the crosslinking reagent, DL-diepoxybutane (DEB), stabilized this conformer so that it retained its structure even when returned to conditions that favored reversion to the B conformation. Treatment of the crosslinked Z conformer with periodate caused scission of the crosslink, allowing reversion to the B conformer. Reaction of (dG-dC)n .(dG-dC)n in the B conformation with DEB did not prevent conversion to the Z conformer in 4M NaCl; dialysis of the high salt solution against low ionic strength buffer allowed return to the B conformer. The Z
B transitions were followed by circular dichroism studies and immunochemical procedures. The results suggest the feasibility of stabilizing Z sequences of DNA In chromatln by crosslinking, so that they could then be identified after DNA isolation.