Nucleic Acids Research, 1992, Vol. 20, No. 6 1223-1228
© 1992
CHEMISTRY |
The formation of A-DNA in NaDNA films is suppressed by netropsin
Institute of Microbiology and Experimental Therapy, Jena, Beutenbergstrasse 11 D-O-6900 Jena, Germany 1University of California San Francisco, VAMC 11-M 4150 Clement St., San Francisco, CA 94121, USA 2Division of Physical Chemistry, Arrhenius Laboratory, University of Stockholm S-106 91 Stockholm, Sweden 3Max-Planck-lnstitut fur Festkorperforschung, Heisenbergstrasse 1 7000 Stuttgart 80, Germany 4Department of Chemistry, University of California San Diego, La Jolla, CA 92093, USA
*To whom correspondence should be addressed
Received January 28, 1992. Accepted February 17, 1992.
Oriented films of NaDNA complexed with netropsin were studied with deuterium nuclear magnetic resonance (2H NMR), X-ray diffraction and ultraviolet (UV) linear dichroism to obtain Information about the influence of netropsin on the structural arrangement of the DNA bases and on the B-A transition. The results of these studies clearly demonstrate a strong suppression of the formation of A-DNA at relative humidities (RHs) down to about 50%. The suppression was complete in the NaDNA-netropsin complex studied with 2H NMR which had a netropsin input ratio, r, of 0.22 drug/base pair. The sample used for UV linear dichroism had a similar input ratio while the X-ray diffraction samples had input ratios between 0.033 and 0.39 drug/base pair. Together, the results of these studies are in agreement with previous infrared (IR) linear dichroism studies of the conformation of the sugar-phosphate backbone in NaDNA-netropsin complexes, which showed that the B-A transition is suppressed for r-values down to approximately 0.1 drug/base pair (Fritzsche, H., Rupprecht, A. and Richter, M., Nucleic Acids Res. 12 (1984) 9165–9177).