On the influence of low-energy ionizing radiation on the amino acid molecule: proline

Low-energy interactions related to atmospheric and extreme conditions

“…This study showed that when cysteine is chemisorbed through the thiol group onto a clean gold substrate, ion yields of hydroxyl anions increased; this also held true for heavier fragments when compared to desorption yields from physisorbed films [1]. Mass spectrometry also was used to investigate fragmentation of another amino acid, proline [2]; however, in contrast to the cysteine work, this study focused on cation formation from a gas-phase molecule. Tamuliene et al reported the ionization energy of proline and the appearance energies of the main cationic fragments produced in LEIs [2].…”

“…-low-energy interactions of charged particles (electrons [1][2][3][4][5][6][7], protons [8], positrons [9]), and photons [10] with atoms and molecules of biological [1][2][3][4]7,8], astrochemical [10], industrial, and environmental [5,6,9] interest; -molecular evolution of astrochemical ices [11][12][13]; -planetary atmospheric physics [14]; -atmospheric pressure photoionization and fragmentation of organic and inorganic aerosols [15]; -processes and applications of atmospheric pressure plasmas in astrochemical [16,17] and biomedical fields [17,18].…”

“…These works focused on fragmentation of cysteine [1] and proline [2] induced by low-energy electrons through the processes of dissociative electron attachment and electron impact ionization, respectively. Alizadeh et al demonstrated ion desorption yields from physisorbed and chemisorbed cysteine films irradiated by electrons [1] and measured using mass spectrometry.…”

“…Mass spectrometry also was used to investigate fragmentation of another amino acid, proline [2]; however, in contrast to the cysteine work, this study focused on cation formation from a gas-phase molecule. Tamuliene et al reported the ionization energy of proline and the appearance energies of the main cationic fragments produced in LEIs [2]. The authors supported their fragment assignment by calculating the appearance energies of different proline conformers.…”

“…The authors supported their fragment assignment by calculating the appearance energies of different proline conformers. Moreover, they determined the possible dissociation mechanism of the dominant fragmentation pathway, in which one electron is removed from the lone pair of the nitrogen atom, and results eventually in the cleavage of the C-C α bond accompanied by the loss of COOH [2]. A theoretical investigation of total cross sections of electron impact in a wide energy range, from the ionization threshold to 5 keV, also was performed for tetrahydrofuran [4].…”