A NEXAFS and mass spectrometry study of cysteine, cystine and insulin irradiated with intermediate energy (0.8 keV) electrons Simões, G., E-mail: simoes.grazieli@gmail.com [Instituto de Química, Universidade Federal do Rio de Janeiro, Cidade Universitária, 21941-909 Rio de Janeiro (Brazil)]; Rodrigues, F. N. [Instituto de Química, Universidade Federal do Rio de Janeiro, Cidade Universitária, 21941-909 Rio de Janeiro (Brazil)]; Instituto Federal de Educação, Ciência e Tecnologia do Rio de Janeiro, Maracanã, 20270-021 Rio de Janeiro (Brazil)]; Bernini, R. B. [Instituto de Química, Universidade Federal do Rio de Janeiro, Cidade Universitária, 21941-909 Rio de Janeiro (Brazil)]; Instituto Federal de Educação, Ciência e Tecnologia do Rio de Janeiro, Duque de Caxias, 25050-100 Rio de Janeiro (Brazil)]; Castro, C. S.C. [Instituto Nacional de Metrologia, Qualidade e Tecnologia – Inmetro, 25250-020 Rio de Janeiro (Brazil)]; Souza, G. G.B. de, [Instituto de Química, Universidade Federal do Rio de Janeiro, Cidade Universitária, 21941-909 Rio de Janeiro (Brazil)] 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ABSORPTION SPECTRA; ABSORPTION SPECTROSCOPY; CYSTEINE; CYSTINE; FINE STRUCTURE; INSULIN; IRRADIATION; MASS SPECTROSCOPY; SULFUR; X-RAY SPECTROSCOPY Highlights: • Structural modifications in sulfur containing biomolecules were investigated. • Significant modifications were observed in insulin irradiated NEXAFS spectra. • Degradation of insulin can be observed even at low temperature. • Alterations in insulin spectrum were characterized according to the state of sulfur. - Abstract: We have performed a NEXAFS (S 1s) and mass spectrometry study of solid samples of cysteine, cystine and insulin irradiated with 0.8 keV electrons. The measured mass spectra point out to processes of desulfurization, deamination, decarbonylation and decarboxylation in the irradiated biomolecules. Electron beam irradiation was also conducted at low temperatures in order to evaluate the possible contribution from thermal degradation processes. The NEXAFS spectra of irradiated cysteine and cystine did not show substantial changes when compared to the same spectra obtained using non-irradiated samples. The sulfur K-edge photoabsorption spectrum of irradiated insulin, however, showed clear modifications when compared to the spectrum of the non-irradiated protein, even when the irradiation was conducted at low temperature. Using an empirical combination of the photoabsorption spectra of cysteine and cystine (which are associated respectively with reduced and oxidized forms of sulfur) we have been able to reproduce the absorption spectrum of irradiated insulin. Available from http://dx.doi.org/10.1016/j.elspec.2014.02.002 Netherlands 2014-03-01 English Journal Article Journal Name: Journal of Electron Spectroscopy and Related Phenomena; Journal Volume: 193; Other Information: Copyright (c) 2014 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: Austria Medium: X; Size: page(s) 21-26 https://doi.org/10.1016/J.ELSPEC.2014.02.002 PII: S0368-2048(14)00041-3 [] 193 Journal ID: ISSN 0368-2048; CODEN: JESRAW; Other: PII: S0368-2048(14)00041-3; TRN: NL15R1394051020 NLN 2015-06-19 22344686