Studies on DNA polymorphism.
Possible variations in the secondary structure and the A V---4 B
transition in DNA's of varying primary base sequence and composition have
been studied by the techniques of X-ray diffraction and molecular model
building. The DNA's studied are from both bacteria and from
eukaryotic cells. In addition a DNA of viral origin, from the bacteriophage
OW-14, has been investigated.
A computerised model building study of the changes induced
in DNA secondary structure by the binding of intercalating drugs has
also been carried out.
A linked atom least squares routine has been extended and used
to refine the models presented. The routine enables standard values
for the parameters defining the covalent stereochemistry of the structure
to be retained. Methods of calculating the Fourier transforms of the
models produced are discussed, and this enables some comparisons to be
made between the observed diffraction data and those predicted by the
Structures studied include the intercalation complexes involving
ethidium or daunomycin, general intercalation models for DNA and models
for the conformation of the putrescene groups in OW-14 DNA.