The long term objectives of this research is to provide detailed understanding at the molecular level on the binding of some models drugs to DNA, through which rational design of effective anticancer drugs can hopefully be based. This proposal will focus on sequence specific binding and kinetic studies of three ligands having distinctly different binding modes: actinomycin D (ACTD), a guanine specific intercalator; mithramycin (MTR), a guanine specific minor groove binder; and distamycin A (DST), an A: T specific groove binder. The elucidation of any possible synergistic effect of these drugs will also be made, as they may have relevance in combination chemotherapy DNA dodecamer containing a tetranucleotide-XGCY- or XCGY-sequence at the center and A/T flanking sequences on both sides; to elucidate sequence specific binding of ACTD, MTR, and DST through spectroscopic titration and gel-shift studies with these oligomers; to investigate sequence dependent kinetic behaviors of these drugs via association and detergent induced dissociation rate measurements; to study the effect of A: T-specific DST binding at the flanking sequences on the binding characteristics of guanine-specific MTR or ACTD at the center, and vice versa. in order to elucidate any possible synergistic effect on the binding affinities and kinetics of these drugs; to carry out differential scanning calorimetric measurements of these oligomers for the purpose of obtaining a self-consistent set of thermodynamic functions for all 10 Watson-Crick DNA nearest-neighbor interactions; to obtain thermodynamic parameters of drug complexation of these oligomers via optical and calorimetric parameters of drug complexes for the purpose of obtaining more detailed and specific structural and binding information; and to guide students in developing good research techniques and methodologies, and to expose them to the operations and principles of some modern instrumentations employed in biophysical research.
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