Tautomers of a Fluorescent G Surrogate and Their Distinct Photophysics Provide Additional Information Channels |
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| Authors: | Marianna Sholokh Dr Roberto Improta Dr Mattia Mori Rajhans Sharma Dr Cyril Kenfack Dr Dongwon Shin Dr Karine Voltz Dr Roland H Stote Prof Dr Olga A Zaporozhets Prof Dr Maurizio Botta Prof Dr Yitzhak Tor Prof Dr Yves Mély |
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| Institution: | 1. Laboratoire de Biophotonique et Pharmacologie, Faculté de Pharmacie, UMR 7213 CNRS, Université de Strasbourg, Illkirch, France;2. Department of Chemistry, Kyiv National Taras Shevchenko University, Kyiv, Ukraine;3. Consiglio Nazionale delle Ricerche, Istituto di Biostrutture e Bioimmagini, Napoli, Italy;4. Dipartimento di Biotecnologie, Chimica e Farmacia, Università degli Studi di Siena, Siena, Italy;5. Center for Life Nano Science@Sapienza, Istituto Italiano di Tecnologia, Roma, Italy;6. Laboratoire O'Optique et Applications, Centre de Physique Atomique Moléculaire et Optique Quantique, Université de Douala, Douala, Cameroon;7. Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, USA;8. Department of Integrative Structural Biology, Institut de Génétique et de Biologie Moléculaire et Cellulaire, INSERM U964 UMR 7104 CNRS, Université de Strasbourg, Illkirch, France |
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| Abstract: | Thienoguanosine (thG) is an isomorphic nucleoside analogue acting as a faithful fluorescent substitute of G, with respectable quantum yield in oligonucleotides. Photophysical analysis of thG reveals the existence of two ground‐state tautomers with significantly shifted absorption and emission wavelengths, and high quantum yield in buffer. Using (TD)‐DFT calculations, the tautomers were identified as the H1 and H3 keto‐amino tautomers. When incorporated into the loop of (?)PBS, the (?)DNA copy of the HIV‐1 primer binding site, both tautomers are observed and show differential sensitivity to protein binding. The red‐shifted H1 tautomer is strongly favored in matched (?)/(+)PBS duplexes, while the relative emission of the H3 tautomer can be used to detect single nucleotide polymorphisms. These tautomers and their distinct environmental sensitivity provide unprecedented information channels for analyzing G residues in oligonucleotides and their complexes. |
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| Keywords: | ab initio calculations fluorescence molecular modeling nucleic acids tautomerism |
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