engleski

New Permanently Charged Phenantridinium-Nucleobase Conjugates. Interactions with Nucleotides and Polynucleotides and Recognition of ds-PolyAH, J.

N-Methyl-8-aminophenathridinium-uracil and - adenine conjugates possessing a nucleobase attached at the phenanthridinium 8-amino group by trimethylene spacer were prepared in the form of water soluble hydrogensulfate salts. Spectroscopic characteristics of the conjugates reveal a formation of folded conformations in water characterised by intramolecular aromatic stacking between phenanthridinium unit and the tethered nucleobase. The conjugates form 1:1 complexes in water with either complementary or non-complementary nucleotides giving the log Ks values of 1-2 and showing a lack of any base recognition. Also the binding studies with ss-polynucleotides showed no preference of conjugates toward polynucleotides containing complementary nucleobases. However, at pH 5, the N-methylphenan-thridinium-adenine conjugate exhibited a preferred binding to double stranded (ds-) polyAH+, while its protonated analogue bound preferably to poly U. The results reveal that the presence of protonated or permanently charged intercalator units in the conjugates dramatically changes their binding preferences toward polynucleotides.

phenanthridinium-adenine conjugate; dsAH+; nucleotides; polynucleotides

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