|Institution:||Univerzitet u Beogradu|
|Keywords:||Masena spektrometrija; Akciona spektroskopija; Foto-disocijacija; Elektronski indukovana disocijacija; Sinhrotronsko zraenje; Linearna kvadrupolna jonska zamka; Peptidi; Proteini; Hidratisani nukleotidi|
|Full text PDF:||https://fedorabg.bg.ac.rs/fedora/get/o:15173/bdef:Content/get|
Physics - Atomic and molecular physics / Fizika -Fizika atoma i molekula In an effort to understand the vast complexity ofthe underlying processes within a cell at a molecular level, thefirst step lies in revealing the fundamental physical and chemicalproperties, as well as the structure, of biopolymers (proteins andDNA). With the development of modern experimental techniques it hasbecome possible to study these large molecules under well-definedconditions in the gas phase, by closely inspecting theirinteractions with energetic photons and electrons. In this Thesis,we present the experimental setups for the action spectroscopy ofpeptides, proteins and nucleotides, as well as the hydratedcomplexes (hydrated nucleotides), in the gas phase. We present thedetails and the operation of the two experimental setups based oncoupling the linear quadrupole ion trap with: (1) a VUV or a softX-ray synchrotron beamline and (2) a focusing electron gun. In thecase (1), the existing experimental setup consisting of acommercial quadrupole ion trap mass spectrometer (LTQ XL fromThermo Scientific), equipped with an electrospray ion source, wascoupled to the VUV beamline DESIRS and the soft X-ray beamlinePLEIADES at the synchrotron SOLEIL (France). The setups were usedto study the photo-induced ionization/fragmentation of trappedbiopolymers and nanosolvated species. The results obtained withthis setups include VUV action spectroscopy of protonatedLeucine-Enkephalin peptide (both a monomer and a dimer) and ananosolvated nucleotide Adenosine monophosphate (AMP), in (5-15) eVphoton energy range. The inner-shell action spectroscopy in thesoft X-ray energy range (around C and N K-edge), was performed formultiply charged precursor of Ubiquitin protein. Thephoto-dissociation and photo-fragmentation ion yields for severalfragment ions from all above mentioned macromolecules wereextracted and the obtained spectral features were discussedconsidering relevant photon-induced processes. In the case (2), newexperimental setup was developed by coupling the same LTQ XL iontrap with a focusing electron gun, in order to perform an electronactivation tandem mass spectrometry, as well as an electron-impactaction spectroscopy of trapped biopolymer ions. The ion opticsimulations using SIMION program were performed in order toinvestigate the propagation of the electron beam in the RF+DC iontrap. Tests measurements for electron-induced fragmentation ofSubstance P, Melittin and Ubiquitin are presented for the impactenergy of 300 eV. Finally, we present the electron-impactinner-shell action spectroscopy of the multiply charged Ubiquitinprotein, in the vicinity of C K-edge energies of (280-300) eV. Theelectron-impact results are compared with the soft X-rayphoton-impact action spectroscopy results obtained for the sametarget.Advisors/Committee Members: Milosavljevi, Aleksandar, 1973-.