Lori McFail-Isom

DNA structure: cations in charge?

Recent X-ray diffraction, NMR spectroscopy and molecular mechanics results suggest that monovalent cations selectively partition into the minor groove of AT-tracts in DNA. These observations are consistent with DNA deformation by electrostatic collapse around areas of uneven cation density. This model predicts the occurrence of known DNA deformations, such as AT-tract bending and changes in the minor-groove width.

Scanning probe visualization of electrostatically immobilized intercalating drug-nucleic acid complexes

DNA intercalators are planar molecules that insert between the base pairs of duplex DNA. Intercalation into DNA necessarily results in changes in DNA conformation, separating base pairs along the helical axis; thus, intercalators are of great importance as probes of nucleic acid structure and as interferents of DNA replication, transcription, and/or topoisomerase activities. Relationships between structures of intercalators and the changes they cause in DNA conformation are subtle and remain unresolved. An intercalating drug molecule has been synthesized that incorporates markers easily distinguished by atomic force microscopy (AFM). This specially designed psoralen derivative has been intercalated into DNA. To facilitate recognition of the point of intercalation, the psoralen derivative contained a biotin moiety that was exposed and bound readily to streptavidin‐coated colloidal gold beads. Atomic force micrographs were obtained following electrostatic immobilization of the DNA/psoralen complexes onto mi...