Electrostatic components of drug—receptor recognition. - II. The DNA-binding antibiotic actinomycin

Abstract

The semiempirical molecular orbital method PCILO [porturbative configuration interaction by means of localized orbitals] was used to study the electronic charge distribution and conformation of the antibiotic actinomycin. Molecular electrostatic potential fields were constructed in 3-dimensional space round the molecule and displayed stereoscopically together with contour maps in the orthogonal planes relative to that of the chromophore. The drug has a considerable dipole moment and that the electrostatic fields can be separated into 2 large regions; an area of positive potential surrounds the chromophore and 1 of negative potential is directed away from the peptide rings. These observations are discussed with respect to drug-receptor recognition phenomena. Pattern-matching of complementary electrostatic fields between the drug and polynucleotide receptor can be discerned.