Mass spectrometry of processes of dissociative ionization of glutamine molecules


Background. Recently the interest in the radiation-implication-study of amino acids has rapidly increased due to the fundamental importance of the molecules of amino acids. Amino acids belong to biologically relevant organic substances involved in the live organisms. They serve as building blocks of proteins and intermediates in metabolism. The chemical properties of amino acids determine the biological activity of the proteins. The latter do not only catalyze most of the reactions in living cells, they also control all cellular processes. In addition, proteins contain the necessary information needed to determine the structure and the stability of the human body. The availability of such experimental data is the basis for developing new or improving existing theoretical models.
Methods. The electron-impact ionization mass-spectrometric technique was used being combined with the method of normally crossed molecular and electron beams. The experiments were carried out using a modified magnetic МИ-1201 mass-spectrometer. The mass-spectra of the above molecules have been measured together with the energy dependences of their ionization and dissociative ionization cross-sections.
Results. The work represents the mass-spectra of the glutamine molecules measured at energy of ionizing electrons 70 eV. The principal mass-spectra peaks have been identified. Despite the low relative intensity of the fragment ions, the energy dependences of their yield and the ionization potentials (energies) have been measured and obtained, respectively. The absolute values of the appearance energies of the main ionic fragments of the molecules under study have been determined.
Conclusions. The paper presents new data on the electron-impact fragmentation of the amino acid glutamine molecule and they are presented as being related to the formation of the ionized products due to the influence of low-energy ionizing radiation on the above molecule. A series of the produced fragments have been identified. The absolute appearance energies for some of them have been measured experimentally

Keywords: molecule, ionization, glutamine, mass-spectrometry