Received 21.06.2022, Revised 21.06.2022, Accepted 21.06.2022
https://doi.org/10.54919/2415-8038.2022.51.9-17
Relevance. Valine is one of the eight amino acids not synthesised by the human body, necessary for the synthesis and growth of body tissues, muscle coordination; regulation of nervous processes, nitrogen metabolism, and stabilisation of the hormonal background. Since α-amino acids contain an asymmetric carbon atom, they can exist as optical isomers (mirror antipodes) that play an essential role in protein biosynthesis. The structure of matter and the physical processes that occur in it are studied using the method of mass spectrometry and spectral analysis. This indicates the relevance of the problem that was studied in this paper.
Purpose. Mass spectrometric studies of the formation of ionic products of single and dissociative ionisation of the valine molecule (C5 H11NO2) with electrons according to the method of beams intersecting within the energy range of bombarding electrons 6-70 eV. To consider the mechanisms of formation of the most intense ion fragments during dissociative ionisation by electron shock.
Methods. The experiment was conducted on an installation with a monopole mass spectrometer of the MX-7304A type, which belongs to the class of dynamic mass analysers with electron shock ionisation in the range of mass numbers 0-120 Da. The mass spectra of molecules were investigated at different temperatures of the source of molecules in the range of 300-600 K.
Results. The obtained results are compared with the mass spectra of the D-, L-, and DL-enantiomeric forms of the valine molecule with data from the NIST and SDBS databases. The features of the processes of formation of ion fragments of valine molecules by electronic shock are analysed in detail, and the dynamics of the yield of ion fragments in the range of evaporation temperatures of the initial substance of 300-440 K is also studied. The total relative ionisation cross-section of the molecule under study was measured according to mass spectrometric method with an ionising electron energy of 5-60 eV. Based on the results of experimental studies, a threshold section of the dependence of the total relative cross-section of valine ionisation is determined and given in this paper.
Conclusions. A detailed analysis of the processes of formation of fragment ions in the mass spectra allows demonstrating the influence of the structural forms of valine enantiomers on the redistribution of relative intensities of product ions
Keywords: electron, mass spectrometry, ionisation, amino acid
[1] Sonntag C. The chemical basis for radiation biology. London: Taylor & Francis press; 1987. 515 p. doi: 10.1080/09553008714552571.
[2] Ward JF. Advances in radiation biology. New York: Academic Press; 1977. Volume 5, Molecular Mechanisms of Radiation-Induced Damage to Nucleic Acids; p. 181-239.
[3] Golichenko BO, Naseka VM, Strelchuk VV, Kolomys OF. Raman study of L-Asparagine and L-Glutamine molecules adsorbed on aluminum films in a wide frequency range. Semiconductor Physics, Quantum Electronics & Optoelectronics. 2017;20(3):297-304. doi: 10.15407/spqeo20.03.297.
[4] Bulhakova AI, Zavilopulo AM. Mass spectrometric studies of the glutamine molecule. Scientific Herald of Uzhhorod University. Series “Physics”. 2018;(44):141-47. doi: 10.24144/2415-8038.2018.44.141-147.
[5] Inokuti M. Atomic and molecular data needed for radiotherapy and radiation research. Vienna: IAEA Press; 1995. 754 p.
[6] Sanche L. (2006). Interaction of low energy electrons with DNA: Applications to cancer radiation therapy. Radiation Physics and Chemistry. 2006;(128):36-43. doi: 10.1016/j.radphyschem.2016.05.008.
[7] Erdevdi NM, Bulhakova AI, Shpenik, OB, Zavilopulo AN. (2020). Electron-impact-induced excitation of glutamine molecules. Technical Physics Letters. 2020;(46):815-18. doi: 10.1134/S1063785020080209.
[8] Monteiro WA. Radiation effects in materials. London: IntechOpen; 2016. 462 p. doi: 10.5772/61498.
[9] Fabrikant II, Eden S, Mason NJ, Fedor J. Chapter nine – recent progress in dissociative electron attachment: From diatomics to biomolecules. Advances in Atomic, Molecular, and Optical Physics. 2017;(66):546-641. doi: 10.1016/bs.aamop.2017.02.002.
[10] Hu Y, Bernstein ER. Vibrational and photoionization spectroscopy of biomolecules: Aliphatic amino acid structures. Journal of Chemical Physics. 2008;(128):164311. doi: 10.1063/1.2902980.
[11] Zavilopulo AN, Mironets EA, Agafonova AS. (2012). An upgraded ion source for a mass spectrometer. Instruments and Experimental Techniques. 2012;(55):65-71. doi: 10.1134/S0020441211060315.
[12] Zavilopulo AN, Shpenik OB. Electron-impact mass spectrometry of PTCDA molecules in the gas phase. Ukrainian Journal of Physics. 2019;64(1):3. doi: 10.15407/ujpe64.1.3.
[13] NIST standard reference database [Internet]. National Institute of Standards and Technology USA; n.d. [updated 2022; cited 2022 June 23]. Available from: https://webbook.nist.gov/.
[14] Spectral Database for Organic Compounds SDBS [Internet]. National Institute of Advanced Industrial Science and Technology. Japan; n.d. [updated 2022 March 31; cited 2022 June 23]. Available from: https://sdbs.db.aist.go.jp.
[15] Papp P, Shchukin P, Kocisek J, Matejcik SJ. (2012). Electron ionization and dissociation of aliphatic amino acids. The Journal of Chemical Physics. 1012;(37):105101. doi: 10.1063/1.4749244.
[16] Jochims, H-W, Schwell M, Chotin J-L, Clemino M, Dulieu F, Baumgärtel H, et al. (2004). Photoion mass spectrometry of five amino acids in the 6-22 eV photon energy range. Chemical Physics. 2004;298(1-3):279-97. doi: 10.1016/j.chemphys.2003.11.035.
[17] Smirnov OV, Basalaev AA, Boitsov VM, Vyaz’min SYu, Orbeli AL, Dubina MV. (2014). Fragmentation of D- and L-enantiomers of amino acids through interaction with 3He2+ ions. Technical Physics. 2014;(59):1698-704. doi: 10.1134/S1063784214110231.
[18] Meierhenrich U. Amino acids and the asymmetry of life. Berlin: Springer-Verlag; 2008. 264 p. doi: 10.1007/978-3-540-76886-9.
[19] Zavilopulo AN, Shpenik OB, Mylymko AN, Shpenik VYu. Mass spectrometry of d-ribose molecules. International Journal of Mass Spectrometry. 2019;(441):1-7. doi: 10.1016/j.ijms.2019.03.008.
[20] Song X, Li J, Hou H, Wang B. Ab initio study of the potential energy surface for the OH+CO→H+CO2 reaction. Journal of Chemical Physics. 2006;(125):094301. doi: 10.1063/1.2347711.
[21] Nuevo M, Meierhenrich UJ, Munoz Caro GM, Dartois E, d’Hendecourt L, Deboffle D, et al. The effects of circularly polarized light on amino acid enantiomers produced by the UV irradiation of interstellar ice analogs. Astronomy & Astrophysics. 2006;(457):741-51. doi: 10.1051/0004-6361:20042018.
[22] Ostroverkh A, Zavilopulo A, Shpenik O. Ionization of guanine, adenine and thymine molecules by electron impact. The European Physical Journal D. 2019;(73):38. doi: 10.1140/epjd/e2019-90532-3.
[23] Choi MY, Miller RE. Four tautomers of isolated guanine from infrared laser spectroscopy in Helium nanodroplets. Journal of the American Chemical Society. 2006;128(22):7320-8. doi: 10.1021/ja060741l.
[24] Zavilopulo AN, Shpenik OB, Markush PP, Kontrosh EE. Ionization of glycerin molecule by electron impact. Technical Physics. 2015;(60):957-63. doi: 10.1134/S1063784215070282.
[25] Klasinc L. Application of photoelectron spectroscopy to biologically active molecules and their constituent parts: III. Amino acids. Journal of Electron Spectroscopy and Related Phenomena. 1976;(8):161-4. doi: 10.1016/0368-2048(76)80018-7.
[26] Berry RS, Leach S. Elementary attachment and detachment processes. II. Adv. Electron. Electron Phys. 1981;(57):1. doi: 10.1016/S0065-2539(08)60362-5.
[27] Close DM. (2011). Calculated vertical ionization energies of the common α-amino acids in the gas phase and in solution. Journal of Physical Chemistry A. 2011;115(13):2900-12. doi: 10.1021/jp200503z.
[28] Dehareng D, Dive G. (2004). Vertical ionization energies of α-l-amino acids as a function of their conformation: An Ab initio study. International Journal of Molecular Sciences. 2004;5(11):301-32. doi: 10.3390/i5110301.
[29] Vukstich VS, Romanova LG, Megela IG, Papp AV, Snegurskii AV. Fragmentation of a valine molecule by electron impact. Technical Physics Letters. 2017;(43):416-20. doi: 10.1134/S1063785017050133.