Исследование электронной структуры дезоксириБозно-нуклеиновой кислоты

Abstract

The results obtained for the approximate quantum mechanical ρ-electron overlap integrals between the parallel nucleotide bases of DNA at a distance of 3,36 A from one another indicate the existence of a non-negligible ρ-electron interaction between the adjacent bases of DNA. In order to carry out the calculations, details of which are given in the Appendix, it was necessary to construct approximately the lowest LCAO MO-s of the pyrimidine and purine ring and a screw rotation of 36° between the adjacent bases around the axis of the helix relative to each other had to be taken into consideration. This paper endeavours to explain the great biological effect of physical or chemical changes localized in small parts of DNA (the effect of X-ray-, particle beam and ultraviolet irradiation; spontaneous mutation due to the alteration of the sequence in one point) by taking into account the mobility of the electrons along the long axis of the DNA macromolecule. Further, it shows the possible genetical importance of the fact that on the basis of the different overlap integral values between the different rings it may be expected that the electron distributions belonging to the various base sequences of DNA differ from one another. On the basis of the calculations it was possible to give an interpretation of the important role which the substitution on the C atom 5 in the pyrimidine ring is playing from a biological point of view. Finally, the paper deals with the possibility of explaining the so-called anomalous absorption of the ultraviolet spectrum of DNA by means of the ρ-electron interaction between the bases.