Guanine-aspartic acid interactions probed with IR-UV resonance spectroscopy

• Published in: Physical chemistry chemical physics : PCCP 2010-01, Vol.12 (14), p.3597-3605
• Main Authors: Crews, Bridgit O, Abo-Riziq, Ali, Pluhácková, Kristýna, Thompson, Patrina, Hill, Glake, Hobza, Pavel, de Vries, Mattanjah S
• Format: Article
• Language: English
• Subjects: Aspartic Acid - chemistry; Guanine - chemistry; Hydrogen Bonding; Models, Molecular; Molecular Probes; Spectrophotometry, Infrared - methods; Spectrophotometry, Ultraviolet - methods
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/b925340h

Double resonance spectroscopy of clusters of guanine with aspartic acid reveals geometries similar to patterns exhibited in DNA base pairs. In the spectral region of 32,800 cm(-1) to 35,500 cm(-1) we observe five isomers of guanine-aspartic acid clusters and assign their structures based on IR-UV hole-burning spectra and wave function theory calculations at the MP2/cc-pVDZ and MP2/cc-pVTZ levels. The calculations employed both harmonic and one-dimensional scan anharmonic approximations. Three of the isomers are similar, assigned to structures containing three hydrogen bonds and 9-enolguanine. We assign the fourth isomer to a structure containing a 9-keto tautomer of guanine and forming a triply bonded structure similar to a base pairing interaction. The fifth isomer dissociates with proton transfer upon excitation or ionization. This is the first set of experiments and high-level ab initio calculations of the isolated, microscopic interactions of an amino acid and a nucleobase, the building blocks of nucleic acids and proteins.