Distinguishing co-existing unimolecular and bimolecular structural forms using joint analysis of Raman and UV absorption data

• Published in: Journal of Raman spectroscopy 2015-02, Vol.46 (2), p.244-250
• Main Authors: Pečínková, Pavla, Bok, Jiří, Hofbauerová, Kateřina, Štěpánek, Josef
• Format: Article
• Language: English
• Subjects: Mathematical models; oligonucleotide; Oligonucleotides; Raman scattering; Raman spectra; Ribonucleic acids; RNA; Spectra; Structural forms; thermodynamic stability; Thermodynamics; UV absorption
• ISSN: 0377-0486; 1097-4555
• DOI: 10.1002/jrs.4610

Standard Raman measurements of solutions require relatively high concentration of dissolved species, which supports formation of intermolecular complexes. In case of simultaneous presence of unimolecular and bimolecular structural forms, it is often difficult or even impossible to discriminate between them by using only the Raman data. We present a possible and effective way how to combine temperature dependencies of Raman scattering and UV absorption in a joint thermodynamic analysis. This approach is based on a joint fit of the results of multivariate analysis (singular value decomposition) of individual Raman and UV absorption spectral sets to a thermodynamic model. Our case study on RNA oligonucleotides, which can form imperfect intermolecular duplexes or intramolecular hairpin structures, demonstrates that this approach allows to determine thermodynamic parameters of co‐existing unimolecular and bimolecular structural forms and to isolate their Raman spectra. Copyright © 2014 John Wiley & Sons, Ltd. It is demonstrated on a case study of RNA strands that form co‐existing imperfect intermolecular duplexes and intramolecular hairpin structures, how to combine results of temperature‐dependent Raman scattering and UV absorption in a joint thermodynamic analysis. This approach allows to determine thermodynamic parameters of co‐existing unimolecular and bimolecular structural forms and to isolate their Raman spectra.