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Triplex Formation by Oligonucleotides Containing Organomercurated Base Moieties
Author(s) -
Ukale Dattatraya Uttam,
Lönnberg Tuomas
Publication year - 2018
Publication title -
chembiochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.05
H-Index - 126
eISSN - 1439-7633
pISSN - 1439-4227
DOI - 10.1002/cbic.201800112
Subject(s) - oligonucleotide , chemistry , pyrimidine , thiophenol , circular dichroism , base pair , stereochemistry , triple helix , intramolecular force , residue (chemistry) , cysteine , crystallography , dna , biochemistry , organic chemistry , enzyme
Homothymine oligonucleotides with a single 5‐mercuricytosine or 5‐mercuriuracil residue at their termini have been synthesized and their capacity to form triplexes has been examined with an extensive array of double‐helical targets. UV and circular dichroism (CD) melting experiments revealed the formation and thermal denaturation of pyrimidine ⋅ purine*pyrimidine‐type triple helices with all oligonucleotide combinations studied. Nearly all triplexes were destabilized upon mercuration of the 3′‐terminal residue of the triplex‐forming oligonucleotide, in all likelihood due to competing intramolecular Hg II ‐mediated base pairing. Two exceptions from this general pattern were, however, observed: 5‐mercuricytosine was stabilizing when placed opposite to a T ⋅ A or A ⋅ T base pair. The stabilization was further amplified in the presence of 2‐mercaptoethanol (but not hexanethiol, thiophenol or cysteine), suggesting a stabilizing interaction other than Hg II ‐mediated base pairing.