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Raman spectroscopic study of triplex‐like complexes of polyuridylic acid with the isopolar, non‐isosteric phosphonate analogues of diadenosine monophosphate
Author(s) -
Hanuš J.,
Chmelová K.,
Štěpánek J.,
Turpin P.Y.,
Bok J.,
Rosenberg I.,
Točík Z.
Publication year - 1999
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/(sici)1097-4555(199908)30:8<667::aid-jrs432>3.0.co;2-5
Subject(s) - chemistry , raman spectroscopy , phosphonate , dimer , titration , stereochemistry , stoichiometry , adenosine monophosphate , crystallography , phosphate , nucleotide , adenosine , organic chemistry , biochemistry , physics , optics , gene
The formation of poly(rU) complexes with diadenosine monophosphate (3′–5′) and its four isopolar, non‐isosteric phosphonate analogues was studied by means of Raman spectroscopic titration. A set of mixed samples containing the diadenosine monophosphate or monophosphonate and the poly(rU) at various concentration ratios was prepared. The room temperature spectra of mixed solutions were treated by factor analysis and decomposition of the Raman marker bands. For all the species studied, the results revealed an exclusive presence of the triplex‐like complexes, i.e. complexes with a 1:2 stoichiometric ratio of the adenosine to uridine units, the Raman spectra of which exhibit all the features typical of the poly(rU)·poly(rA)·poly(rU) triple‐helical structure. The individual molar fractions of the free ApA dimer, the free poly(rU) and the triplex‐like complex do not fit classical equilibrium equation, because the binding ability of the adenosine dimers to poly(rU) falls significantly for small ApA molar fractions. This tendency is strongest for the natural diadenosine phosphate (3′–5′) and weakest for two analogues in which the —CH 2 — group in the modified internucleotide linkage is situated closer to the 5′‐position. Copyright © 1999 John Wiley & Sons, Ltd.