Calculated Microscopic Stability Constants for Deprotonation of the Zwitterions H2cys and H2pen
Supporting Information Theoretical and Experimental Sulfur K-edge X-ray Absorption Spectroscopic Study of Cysteine, Cystine, Homocysteine, Penicillamine, Methionine and Methionine Sulfoxide Emiliana Damian Risberg,1 Farideh Jalilehvand,2 Bonnie O. Leung,2 Lars G.M. Pettersson3 and Magnus Sandström1* 1 Department of Physical, Inorganic and Structural Chemistry, Stockholm University, SE-106 91 Stockholm, Sweden. 2 Department of Chemistry, University of Calgary, Calgary, AB T2N 1N4, Canada. 3 Department of Physics, Alba Nova, Stockholm University, SE-106 91 Stockholm, Sweden. Supporting Information Available: Tables S1, S3: calculated microscopic stability constants for deprotonation of the zwitterions H2Cys and H2Pen. Tables S2, S4, S5: calculated energies and intensities for the numbered transitions in Figs. S6, 17 and S16 for the Cys2-, 2- [Ni(Cys)2] and Hg((HCys)S)2 species, respectively. Fig. S1 displays the fractions of the major cysteine species at different pH values. Figs. S2; S3; S4; S6; S7; S8; S9; S11; S12; S13; S14; S16 show MO contours for the transitions marked in the calculated XANES spectra for + - - - the following (hydrated) species: H3Cys , H2Cys, HCys : thiol (HCys )N and thiolate (HCys )S, 2- - - - 2- Cys , H2Pen, HPen : thiol (HPen )N and thiolate (HPen )S; Pen , homocysteine HS-CH2-CH2- + - + - CH(NH3) COO , methionine CH3S(CH2)2CH(NH3 )COO , methionine sulfoxide CH3-SO- + - - + + - (CH2)2-CH( NH3)-COO , cystine OOC-CH(NH3 )CH2S-SCH2CH(NH3 )COO , and the trans-Hg((HCys)S)2 complex. Fig. S5 displays the experimental S K-edge XANES spectra for reduced and oxidized glutathione in the solid state and in solutions at different pH values, and Figs.
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