Properties of isolated DNA bases, base pairs and nucleosides examined by laser spectroscopy

E. Nir; Ch. Plützer; K. Kleinermanns; M. de Vries

doi:10.1140/epjd/e2002-00167-2

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2024 Impact factor 1.5

Atomic, Molecular, Optical and Plasma Physics

Eur. Phys. J. D 20, 317-329 (2002)
https://doi.org/10.1140/epjd/e2002-00167-2

Properties of isolated DNA bases, base pairs and nucleosides examined by laser spectroscopy

E. Nir¹, Ch. Plützer², K. Kleinermanns²^a and M. de Vries³

¹ Department of Chemistry, The Hebrew University, Jerusalem 91904, Israel
² Institut für Physikalische Chemie und Elektrochemie I, Heinrich Heine Universität Düsseldorf, 40225 Düsseldorf, Germany
³ Dept. of Chemistry and Biochemistry, Santa Barbara, California 93106, USA

Corresponding author: ^a kleinermanns@uni-duesseldorf.de

Received: 16 June 2002
Revised: 15 July 2002
Published online: 13 September 2002

Abstract

The vibronic spectra of laser desorbed and jet cooled guanine (G) adenine (A), and cytosine (C) consist of bands from four, two and two major tautomers respectively, as revealed by UV–UV and IR–UV double resonance spectroscopy. The vibronic spectrum of adenine around 277 nm consists of weak $n\pi^*$ and strong $\pi\pi^*$ transitions, based on IR–UV and deuteration experiments. Precise ionization potentials of G and A were determined with 2-color, 2-photon ionization. We also measured vibronic and IR spectra of several base pairs. GC exhibits a HNH $\cdots$ OH/NH $\cdots$ N/C=O $\cdots$ HNH bonding similar to the Watson-Crick GC base pair but with C as enol tautomer. One GG isomer exhibits non-symmetric hydrogen bonding with HNH $\cdots$ N/NH $\cdots$ N/C=O $\cdots$ HNH interactions. A second observed GG isomer has a symmetrical hydrogen bond arrangement with C=O $\cdots$ NH/NH $\cdots$ O=C bonding. Two CC isomers were observed with symmetrical C=O $\cdots$ NH/NH $\cdots$ O=C bonding and nonsymmetrical C=O $\cdots$ HNH/NH $\cdots$ N interaction, respectively. Guanosine (Gs), 2-DeoxyGs und 3-DeoxyGs each exhibit only one isomer in the investigated wavelength range around 290 nm with a strong intramolecular sugar(5-OH) $\cdots$ enolguanine(3-N) hydrogen bond.