RESUMO
Infrared linear dichroism and X-ray diffraction analysis on oriented films and fibres, respectively, were used simultaneously to elucidate structural characteristics of a DNA-drug complex (the drug was the anticancer antibiotic violamycin BI, an anthracycline derivative). First, the parameters accessible by the two methods are briefly explained; then, attempts to inter-correlate the data from both lines of investigations are made, which demonstrate that they support and supplement each other favourably concerning several structural aspects. This holds, in particular, for results regarding the conformational flexibility of DNA in complexes and the relative amounts of intercalated and outside-bound drug molecules. Thus, the study represents an example for a successful combined application of two physical methods to one biochemical problem.
Assuntos
Aminoglicosídeos , Antibacterianos/metabolismo , DNA/metabolismo , Espectrofotometria Infravermelho , Difração de Raios X , Antibacterianos/farmacologia , Cristalização , DNA/efeitos dos fármacos , Umidade , Conformação de Ácido NucleicoRESUMO
Interaction of distamycin A with calf spleen DNA is investigated by the method of hyperchromic spectra. Hyperchromic spectra of complexes are partitioned into the components corresponding to the denaturation A . T and G . C base pairs and dissociation of the ligand, fractions of respective components are found as a function of temperature. A scheme of melting of successive regions of DNA with different G+C content together with the scheme of distamycin A redistribution in the course of thermal denaturation is presented.
