engleski

Surface-enhanced Raman study of the interactions between cationic polyamines and polynucleotides

Surface-enhanced Raman scattering (SERS) was used to study interactions of new DNA/RNA binding compounds with double-stranded DNA polynucleotides (poly dAdT-poly dAdT, poly dGdC-poly dGdC) and calf thymus DNA (ct-DNA). SERS experiments with double-stranded polynucleotides revealed strong enhancement of the Raman scattering from the polyamine molecules attached on the colloidal silver particles as well as appearance of new bands associated mainly with nucleobases. Im and Py selectively interact with polynucleotides depending on their base pairs structures. Interactions within both, major and minor groove are recognized for poly dAdT-poly dAdT, while the polyamines prefer binding only to major groove of poly dGdC- poly dGdC. In SERS spectra with ct-DNA downshift of the imidazole and pyridine ring vibrations supports aromatic stacking interactions of the aromatic moieties between the DNA base pairs. Although the same binding mode was evidenced for both molecules, more spectral changes were observed for Im. Since Im and Py contain the same aminomethylene chains in molecular structure, differences originate from the aromatic rings. Unlike pyridine, the imidazole ring poses two potential binding sites, obviously responsible for stronger interactions.

surface-enhanced Raman scattering; polyamines; polynucleotides

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