Evidence for a new transition in polyribonucleotides from raman optical activity

Bell, A. F., Hecht, L. and Barron, L. D. (1999) Evidence for a new transition in polyribonucleotides from raman optical activity. Journal of Raman Spectroscopy, 30(8), pp. 651-656. (doi: 10.1002/(SICI)1097-4555(199908)30:8<651::AID-JRS406>3.0.CO;2-F)

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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.

Item Type:Articles
Additional Information:We thank the EPSRC and BBSRC for research grants and the EPSRC for a Senior Fellowship for L.D.B.
Glasgow Author(s) Enlighten ID:Hecht, Dr Lutz and Barron, Professor Laurence
Authors: Bell, A. F., Hecht, L., and Barron, L. D.
College/School:College of Science and Engineering > School of Chemistry
Journal Name:Journal of Raman Spectroscopy
ISSN (Online):1097-4555
Published Online:02 August 1999

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