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An ellipticine derivative (oxazolopyridocarbazolium) 3′ linked to tetrathymidylate stacks intramolecularly with the nearest thymine at low concentration and head‐to‐tail intermolecularly at high concentration
Author(s) -
Bazile D.,
Guittet E.,
Piriou J.M.,
Lebret M.,
Paoletti J.
Publication year - 1990
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.360290619
Subject(s) - chemistry , thymine , nuclear overhauser effect , derivative (finance) , proton nmr , dilution , nuclear magnetic resonance spectroscopy , stereochemistry , ring (chemistry) , computational chemistry , crystallography , analytical chemistry (journal) , dna , organic chemistry , thermodynamics , biochemistry , physics , financial economics , economics
The solution conformation of a tetrathymidylate linked through an ester bond to an ellipticine derivative oxazolopyridocarbazolium (OPC) at the 3′ position was investigated using one‐ and two‐dimensional nmr experiments. Since the total electric charge of the OPC ring may influence self‐association, we first determined the pKa of the oxazole cyclic acidic function. Nuclear Overhauser effect spectroscopy experiments showed that, at low concentration, the OPC stacks intramolecularly with the nearest thymine at the 3′ end. At highest concentration, however, the OPC rings are self‐associated. The stacking constant was calculated using 1 H chemical shift dilution experiment. The conformational model suggested by P‐nmr was tested by molecular mechanics computations.