Evidence for global mobility in the premelting of a polynucleotide from temperature-dependent Raman optical activity

✍ Scribed by Alasdair F. Bell; Lutz Hecht; Laurence D. Barron

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 242 KB
• Volume: 4
• Category: Article
• ISSN: 1075-4261
• DOI: 10.1002/(sici)1520-6343(1998)4:2<107::aid-bspy3>3.0.co;2-2

✦ Synopsis

The backscattered Raman and Raman optical activity (ROA) spectra of poly(rA) -poly(rU) at 20ЊC and 45ЊC in buffered aqueous solution between 650 and 1750 cm 01 are reported. Although the intensity of the majority of the Raman bands increase by varying amounts as the temperature is raised in accordance with the wellknown hypochromic effect, the reverse effect is found for the ROA signals which we attribute to thermal accessibility of a greater number of distinct conformations leading to cancellation of ROA signals. The difference ROA spectrum obtained by subtracting the spectrum recorded at 45ЊC from that recorded at 20ЊC displays a very similar sign pattern to those at both 20ЊC and 45ЊC throughout the spectral region examined. This indicates that the same average structure is maintained in this temperature range and that the thermal fluctuations are correlated through the bases, the glycosidic link, the sugar ring, and the phosphate backbone of both strands. These results indicate that ROA may be a useful new probe of the dynamics of nucleic acid in solution.