Reactivity of polysulfides towards metmyoglobin

CARLLINNI COLOMBO, MELISA; PALERMO, JUAN CRUZ; BOUBETA, FERNANDO M.; DARIO ESTRÍN; BARI, SARA E.

Simposio; Exploring the Frontiers of Chemistry: Challenges of the 2st Century; 2019

Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires (Argentina) y Ben-Gurion of the Negev University (Israel).

P45. REACTIVITY OF POLYSULFIDES TOWARDS METMYOGLOBINMelisa Carllinni Colombo,[a] Juan Cruz Palermo,[b] Fernando Boubeta,[b] Darío Estrin,[a,b] SaraBari,[b][a] Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas yNaturales, Universidad de Buenos Aires [b] Instituto de Química Física de los Materiales, Medio Ambiente y Energía, Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas. melisacc.1999@gmail.com; sara.elizabeth.bari@gmail.comHydrogen polysulfides, H2Sn (n>1), are gaining growing interest because some of the physiological roles formerly attributed to endogenous hydrogen sulfide, H2S, are better described as a consequence of their action.1,2 Particularly, H2Sn with n=2,3 have been demonstrated to be products of the 3-mercaptopyruvate sulfurtransferase,1,3 an enzyme of the H2S biosynthesis. Recent studies on polysulfides speciation in aqueous solution reveal that interconversion occurs, resulting on equilibria that depend on the experimental conditions.4 Also, the currently used chemicals for derivatization may cleave polysulfide chains, and hence the reliable analysis of polysulfide mixtures still represents an analytical challenge in the field. As a consequence of our studies on the reactivity of Na2S and metmyoglobin (FeIIIMb),5 we present herein a study of the kinetics of the interaction of synthetic disodium disulfane, Na2S2, with FeIIIMb at neutral pH, and the strategy to analyze the polysulfide contents of the dissolved Na2S2 preparation. We prepared Na2S2 by the comproportionation of an equimolar mixture of disodium sulfide, Na2S, and sulfur, S8, according to described procedure.6 Although the product matches the UV-vis aqueous spectrum of a commercial vendor, the dissolution in organic solvents aided by cryptands revealed the formation of the blue trisulfide radical anion, S3.-. Derivatization of polysulfide chains of different lengths with benzyl chloride may provide the product composition in solution. Upon reaction with FeIIIMb 8 x 10-6 M, in the presence of aqueous Na2S2 (R disulfane/ Mb = 10, 20, 30; pH 6.8, anaerobic, 25ºC) the reduced hemeprotein, FeIIMb, was formed, following an exponential growth. The reaction is relevant to the understanding of the sulfidemediateddetoxification by hemeproteins,7 and to the metal centered reduction of ferric hemeproteins.(1) Kimura, Y. et. al. Scientific Reports 2015, 5 (1).(2) Nagahara, N. et. al. Biochemical and Biophysical Research Communications 2018, 496 (2), 648.(3) Koike, S. et. al. Free Radical Biology and Medicine 2017, 113, 355.(4) Bogdándi, V. et. al. British Journal of Pharmacology 2019, 176, 646.(5) Boubeta, F. M. et. al. Inorganic Chemistry 2018, 57 (13), 7591.(6) Gao, Y. et. al. Chemistry - A European Journal 2015, 21 (48), 17172.(7) Bostelaar, T. et. al. Journal of the American Chemical Society 2016, 138 (27), 8476.