Biophysical Chemistry 104 (2003) 477–488 0301-4622/03/$ - see front matter  2003 Elsevier Science B.V. All rights reserved. doi:10.1016/S0301-4622Ž03.00035-8 A library of IR bands of nucleic acids in solution Martina Banyay , Munna Sarkar , Astrid Graslund * a b a, ¨ Department of Biochemistry and Biophysics, Arrhenius Laboratories, Stockholm University, Stockholm S-106 91, Sweden a Chemical Sciences Division, Saha Institute of Nuclear Physics, 1yAF, Bidhannagar, Calcutta 700064, India b Received 22 November 2002; received in revised form 24 January 2003; accepted 27 January 2003 Abstract This review presents a compilation and discussion of infrared (IR) bands characteristic of nucleic acids in various conformations. The entire spectral range 1800–800 cm relevant for DNAyRNA in aqueous solution has been y1 subdivided into four sections. Each section contains descriptions of bands appearing from group specific parts of nucleic acid structure, such as nucleobase, base–sugar, sugar–phosphate and sugar moiety. The approach allows comparisons of information obtained from one spectral region with another. The IR band library should facilitate detailed and unambiguous assignment of structural changes, ligand binding, etc. in nucleic acids from IR spectra. Section 2 is aimed at highlighting specific features that are useful for following major changes in nucleic acid structures. Section 2 also concerns some recent results, where IR spectroscopy has been used to obtain semi- , quantitative information on coexisting modes of sugar pucker in oligonucleotides.  2003 Elsevier Science B.V. All rights reserved. Keywords: FTIR; Nucleic acids; Spectral library; Sugar pucker; Band assignment 1. Introduction This review presents a library and a discussion of IR bands observed in Fourier transform infrared (FTIR) studies of nucleic acids in aqueous solu- tion. The collection of assigned IR bands should be helpful in the interpretation of IR spectra obtained in the study of structure and interaction in nucleic acids. Marker bands for different con- formational families (B, A and Z backbone con- formers, N- and S-type of sugars) have been coordinated with marker bands for base-specific interactions, (e.g. base pairing) and conformations *Corresponding author. Tel.: q46-8-162450; fax: q46-8- 155597. E-mail address: astrid@dbb.su.se (A. Graslund). ¨ (anti ysyn). Several useful IR reviews for nucleic acids have been published in the past w1–5x. However, these earlier reviews focus on specific issues of base composition, base pairing and back- bone conformation, and accordingly the informa- tion content in each collection is restricted to IR bands relevant to the specific issue. The present library combines the information given in these earlier collections w1–5x, but also expands the outline by adding data obtained from additional studies. IR spectroscopy has been the method of choice for studying various issues concerning structure and interaction in nucleic acids. IR studies have been performed on single-stranded w6x, double- stranded w7–11x and triple-stranded w12–18x