STUDY OF METHYLENE BLUE INTERACTION WITH SYNTHETIC POLYNUCLEOTIDE POLY(rA)-POLY(rU)

A study of the interaction of methylene blue (MB) with poly(rA)-poly(rU) by the method of fluorescence spectroscopy has been carried out. The data obtained revealed that MB, being a DNA-specific ligand, can bind to double-stranded regions of RNA. In this regard, as in the case of DNA, semi-intercalation was the most preferable mechanism for the binding of this ligand to poly(rA)-poly(rU). On the other hand, non-linear curves of dependence of F0/F on concentration of polynucleotide might result from two binding modes, the second of which was probably of an electrostatic nature. Proceeding from the data obtained, the value of KSV was revealed to be almost an order of magnitude less than for DNA, which may indicate that RNA is a less preferable target for MB.

Interaction of Methylene Blue with Synthetic Polynucleotide Poly(dA)-Poly(dT)

The interaction of methylene blue (MB) with poly(dA)-poly(dT) has been studied. It was revealed that MB binds to this polynucleotide by strong and weak modes. It was shown that the strong binding mode of MB is realized by semi-intercalation. Apart from the strong mode, this ligand binds to AT-sequences by weak electrostatic modes as well. Values of the binding constant [Formula: see text] and number of base pairs [Formula: see text] per binding site of MB for the mentioned modes were determined. It was shown that at the interaction with AT sequences MB does not behave itself as a groove binding compound.

Transient Absorption and Raman Studies on Exciplex Formation Dynamics of Photoexcited Cu(II)(TMpy-P4) With Synthetic Polynucleotide

Exciplex formation dynamics of photoexcited copper(II) tetrakis (4-N-methylpyridyl) porphyrin (Cu(II)(TMpy-P4)) with added poly(dA-dT)2 and poly(dG-dC)2 has been investigated by using femtosecond transient absorption and nanosecond and picosecond transient Raman spectroscopic methods. It was observed that the decay time constant of the exciplex is strongly dependent on the polynucleotide and has a strong correlation with the appearance of new transient Raman bands.