The hydration of nucleic acid duplexes as assessed by a combination of volumetric and structural techniques

✍ Scribed by Tigran V. Chalikian; Jens Völker; A. R. Srinivasan; Wilma K. Olson; Kenneth J. Breslauer

• Publisher: Wiley (John Wiley & Sons)
• Year: 1999
• Tongue: English
• Weight: 163 KB
• Volume: 50
• Category: Article
• ISSN: 0006-3525
• DOI: 10.1002/(sici)1097-0282(19991015)50:5<459::aid-bip1>3.0.co;2-b

✦ Synopsis

Using high precision densimetric and ultrasonic measurements, we have determined, at 25°C, the apparent molar volumes V and the apparent molar compressibilities K S of four nucleic acid duplexes-namely, the DNA duplex, poly(dIdC)poly(dIdC); the RNA duplex, poly(rA)poly(rU); and the two DNA/RNA hybrid duplexes, poly(rA)poly(dT) and poly(dA)poly(rU). Using available fiber diffraction data on these duplexes, we have calculated the molecular volumes as well as the solvent-accessible surface areas of the constituent charged, polar, and nonpolar atomic groups. We found that the hydration properties of these nucleic acid duplexes do not correlate with the extent and the chemical nature of the solvent-exposed surfaces, thereby suggesting a more specific set of duplex-water interactions beyond general solvation effects. A comparative analysis of our volumetric data on the four duplexes, in conjunction with available structural information, suggests the following features of duplex hydration: (a) The four duplexes exhibit different degrees of hydration, in the order poly(dIdC)poly(dIdC) Ͼ poly(dGdC)poly(dGdC) Ͼ poly(dAdT)poly(dAdT) Ϸ poly-