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Synthesis and Stability of GNRA‐Loop Analogs
Author(s) -
Wörner Karlheinz,
Strube Thorsten,
Engels Joachim W.
Publication year - 1999
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/(sici)1522-2675(19991215)82:12<2094::aid-hlca2094>3.0.co;2-h
Subject(s) - chemistry , stacking , inosine , base (topology) , base pair , stereochemistry , loop (graph theory) , crystallography , biochemistry , dna , combinatorics , organic chemistry , adenosine , mathematical analysis , mathematics
Nebularine, 9‐( β ‐ D ‐ribofuranosyl)‐9 H ‐purin‐2‐amine, and inosine phosphoramidites 8 , 16 , and 17 , respectively, were synthesized and incorporated into the GNRA tetraloop at different positions (see Scheme , Table , and Fig. 4 ). The oligomers were investigated by means of UV and CD spectroscopy to address the question of how the individual base‐modified N ‐nucleosides contribute to changes in H‐bonding and base‐stacking interactions within the loop. Several CD spectra are given and compared with each other ( Figs. 5 and 6 ). The exchange of the loop sequence in position 4 and 7 results in a distinct change in base stacking. CD‐Band shifting allows us to advance the hypothesis that a transition from a GNRA‐type towards a UNCG‐type base stacking is observed.