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Evidence for a new transition in polyribonucleotides from raman optical activity
Author(s) -
Bell Alasdair F.,
Hecht Lutz,
Barron Laurence D.
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<651::aid-jrs406>3.0.co;2-f
Subject(s) - raman spectroscopy , chemistry , differential scanning calorimetry , base (topology) , crystallography , stacking , glass transition , transition (genetics) , raman optical activity , calorimetry , stereochemistry , molecule , thermodynamics , polymer , optics , biochemistry , organic chemistry , physics , mathematical analysis , mathematics , gene
Vibrational Raman optical activity (ROA) measurements are reported on single‐stranded poly(rA) and double‐stranded poly(rA)·poly(rU) in the temperature range 2–45 °C. The intensities of one ROA couplet in poly(rA) (centred at ca 1329 cm −1 and sensitive to sugar–base conformation) and three in poly(rA)·poly(rU) (two centred at ca 1252 and 1339 cm −1 and sensitive to sugar–base conformation, and one centred at ca 1681 cm −1 and sensitive to base stacking geometry) are plotted as a function of temperature. All four plots reveal a sharp glass‐like transition at ca 15–18 °C which appears to embrace the entire biopolymer. Since both single‐ and double‐stranded polyribonucleotides show the transition, it does not appear to be primarily associated with base‐pair opening. Differential scanning calorimetry failed to reveal any latent heat, which suggests that it is not a simple first‐order transition. The possibility that the transition might be associated with a freezing of motions between conformational substates, perhaps in conjuction with changes in water structure, is discussed. Copyright © 1999 John Wiley & Sons, Ltd.