ROSSA MAXIMILIANO
Congresos y reuniones científicas
Título:
Exploring MS and IRMPD fingerprints of protonated Watson-Crick and Hoogsteen pairs of (Cytosine-Guanine)H+
Autor/es:
MAXIMILIANO ROSSA; ANDRÉS F. CRUZ ORTIZ; MATÍAS BERDAKIN; PHILIPPE MAÎTRE; GUSTAVO A. PINO
Lugar:
Carlos Paz
Reunión:
Congreso; XIII Encuentro Latinoamericano de Fotoquímica y Fotobiología; 2017
Resumen:
One decade after Watson and Crick (WC) discovered the double-helix structure of DNA, Hoogsteen (Hoo) reported a crystal structure in which the base pair had a different geometry to that reported by WC. While WC isomers are considered as the canonical paring forms in DNA transporting the genetic information, Hoo isomers are associated to the formation of triplex related to several human diseases. Therefore, the development of simple techniques that allow identifying the existence of WC or Hoo isomers is of a broad interest.
In this we report a method to prepare the protonated Cytosine-Guanine (CGH+) pair in solution, either in the WC or Hoo isomeric structures that retain their structure after been transferred to the gas phase by Electro Spray Ionization (ESI) where their finger prints are characterized by mass spectrometry (MS) in an 7T FT-ICR Bruker Apex Qe mass spectrometer and by infrared multiphoton dissociation (IRMPD) spectroscopy with the Free-Electron-Laser (FEL) at CLIO (Centre Laser Infrarouge d´Orsay). Calculations at the DFT level are performed to help the interpretation of the experimental results.
Briefly, the mass fragmentation pattern as well as the IRMPD spectra of the parent ion m/z = 263 (CGH+), strongly depends on the pH of the solution (Figure 1), indicating that different isomers are produced. Therefore, the protonated CGH+ WC or Hoo isomers can be selectively prepared in the solution and this structure is preserved upon vaporization in an ESI source. The MS and IRMPD fingerprints of each isomer allow to unequivocally assign them. This is expected to be applicable as an easy methodology based on MS and/or IRMPD to determine the existence of Hoo pairs associated to diseases and mutations, in real samples.
In this we report a method to prepare the protonated Cytosine-Guanine (CGH+) pair in solution, either in the WC or Hoo isomeric structures that retain their structure after been transferred to the gas phase by Electro Spray Ionization (ESI) where their finger prints are characterized by mass spectrometry (MS) in an 7T FT-ICR Bruker Apex Qe mass spectrometer and by infrared multiphoton dissociation (IRMPD) spectroscopy with the Free-Electron-Laser (FEL) at CLIO (Centre Laser Infrarouge d´Orsay). Calculations at the DFT level are performed to help the interpretation of the experimental results.
Briefly, the mass fragmentation pattern as well as the IRMPD spectra of the parent ion m/z = 263 (CGH+), strongly depends on the pH of the solution (Figure 1), indicating that different isomers are produced. Therefore, the protonated CGH+ WC or Hoo isomers can be selectively prepared in the solution and this structure is preserved upon vaporization in an ESI source. The MS and IRMPD fingerprints of each isomer allow to unequivocally assign them. This is expected to be applicable as an easy methodology based on MS and/or IRMPD to determine the existence of Hoo pairs associated to diseases and mutations, in real samples.
