EXCITON EFFECTS IN DINUCLEOTIDES AND POLYNUCLEOTIDES

The absorption, fluorescence emission and fluorescence excitation spec tra of dinucleoside phosphates adenylyl (3'-->5') adenine (ApA), cytid ylyl (3'-->5') cytidine (CpC), deoxythymidylyl (3'-->5') deoxythymidin e (dTpdT) and guanylyl (3'-->5') guanine (GpG) and polynucleotides pol yadenylic acid (poly-A) and polycytidylic acid (poly-C) C) at 77 K, an d their fluorescence polarization spectra at 130 K, were studied in ne utral ethylene glycol-water glasses (1:1, v/v). For ApA and CpC, the d ifference between the fluorescence excitation and absorption spectra o f the corresponding monomers is suggested to be of exciton nature. The spectral manifestations of exciton interaction between the bases of d TpdT and GpG are weak. The fluorescence emission and excitation spectr a of the polynucleotides are similar to those of the corresponding din ucleoside phosphates, which supports the conclusion that exciton inter action acts no further than two bases.