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This paper reports the spectroscopic characterization of the interaction between polyribonucleotides and D–mannitol. The oligoribonucleotides-D-mannitol (ORNs-D-M) complexes possess an anti-influen...

Background. Complexes of oligoribonucleotides with D-mannitol are highly effective, non-toxic and possess a wide range of biological effects. In particular, such complexes can increase immune reactivity and have antiviral and anti-inflammatory activity. Oligonucleotides without D-mannitol do not have such biological effects. Methods. Spectroscopy of circular dichroism, absorption spectroscopy, fluorescence spectroscopy. Results. During the research, we have observed the decrease of fluorescence intensity of the dye water solution with polyribonucleosides. An additional decrease of intensity was observed in complexes with D – mannitol. The maximum effect was obtained for fluorescent sensor solution with polyadenylate and polycytosine. In the cases of polyguanilate and polyuridine minimum changes were observed. The spectral effect may indicate a more intense interaction between polyadenylate and polycytosine with D-mannitol. Linear absorption was carried out in the temperature range from 25°C to 60°C. We recorded an increase of the magnitude of absorption of the polynucleotides when increasing the temperature in the cases of polyadenylate and polycytosine. The value of the hyperchromic effect is 10% for polyadenylate, and 5% for polycytosine. Additional increase of the amount of hyperchromic effect was recorded in complexes with D¬-mannitol. Circular dichroism spectroscopy has shown spectra with a large difference in the structure of polyadenylate and polycytosine when compared with their complexes with D-mannitol. In the cases of polyguanilate and polyuridine and their complexes with D-mannitol, we observed no change in structure. Based on quantum-chemical calculations, it was established that hydrogen bonds between D-mannitol and polynucleotides can be generated. Also, calculations indicated appreciable changes in charge distribution especially at atoms that can generate hydrogen bonds. Conclusion. The obtained data allow us to assume the presence of an additional D-mannitol helix in the complexes of polynucleotides with D-mannitol. This assumption is also confirmed by the simulation of this complexes with the help of the program package Gaussian 09. That can explained the wide spectrum of antiviral action of the complexes of polynucleotides and D-mannitol against both single and two-spiral viruses.

The interaction between 2′-5′А3oligonucleotides and recombinant α-interferon was studied by MALDI-TOF mass spectrometry and fluorescence spectroscopy methods. The ability of this key protein of antiviral cell defense system to bind up to 5 molecules of oligoadenylates depending on their structure was established. The presence of interaction in oligoadenylate-interferon system was also confirmed by fluorescence studies. Investigated compounds quenched the emission of α-interferon from 40 to 63%. The efficiency of quenching of the fluorescence of α-interferon also depends on the oligoadenylates structure.

The optical absorption, fluorescence, and phosphorescence spectra of RNAs and oligonucleotides of different origin, as well as their mixtures with human albumin are investigated. It is confirmed that the energy structures of DNA, RNA, and complex protein macromolecules are determined mainly by the individual properties of their π-electron systems. The positions of the RNA excited singlet and triplet energy levels obtained by authors' previous work are determined more precisely. It is shown that mainly adenine bases are traps for mobile triplet excitons in RNA (contrary to DNA, in which AT complexes are the triplet traps). The spectral manifestation of the RNA/oligonucleotides-albumin interaction is studied. It turns out that namely the phosphorescence spectra of these compounds due to their sharp structure at 4.2 K are the most suitable for the study of the RNA-albumin interaction. The phosphorescence spectra of albumin-2′5′A3 solvents manifest the penetrative binding of 2′5′A3 to an albumin macromolecule...