title: Characterization of sulfur speciation in low molecular weight subunits of glutenin after reoxidation with potassium iodate and potassium bromate at different pH values using x-ray absorption near-edge structure (XANES) spectroscopy.
abstract: Sulfur speciation in low molecular weight (LMW) subunits of glutenin after reoxidation with potassium iodate and potassium bromate at different pH values, aged subunits of glutenin as well as gluten, and gliadin have been investigated in situ by S K-edge X-ray absorption near-edge structure (XANES) spectroscopy. XANES spectra were analyzed quantitatively using a least-squares fitting routine to provide relative percentage contribution of different sulfur species occurring in the samples. Using potassium iodate and potassium bromate for reoxidation of reduced LMW subunits of glutenin led not only to disulfide states but also to higher oxidation states (sulfoxide state, sulfonic acid state). Strongest oxidation occurred at low pH values. Higher oxidation states were also predominantly detected in the aged subunits of glutenin, whereas the disulfide state was the main sulfur species in gluten and gliadin samples. The results showed that the oxidation state of sulfur prior to oxidation (thiol, disulfide) strongly influences sulfur speciation after oxidation. The choice of the oxidizing reagent seems to be of minor importance.
authors.affiliation: Institute for Plant Diseases, Department of Agricultural and Food Microbiology, University of Bonn, Meckenheimer Allee 168, D-53115 Bonn, Germany. A.Prange@gmx.de
authors.forename: Alexander
authors.initials: A
authors.lastname: Prange
authors.forename: Barbara
authors.initials: B
authors.lastname: Birzele
authors.forename: Johannes
authors.initials: J
authors.lastname: Krämer
authors.forename: Hartwig
authors.initials: H
authors.lastname: Modrow
authors.forename: Reinhold
authors.initials: R
authors.lastname: Chauvistré
authors.forename: Josef
authors.initials: J
authors.lastname: Hormes
authors.forename: Peter
authors.initials: P
authors.lastname: Köhler
mesh_terms: D001959:Bromates / Q000737:chemistry*; D005983:Glutens / Q000031:analogs & derivatives* / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007202:Indicators and Reagents; D007452:Iodates / Q000737:chemistry*; D008970:Molecular Weight; D010084:Oxidation-Reduction; D017680:Potassium Compounds / Q000737:chemistry*; D013057:Spectrum Analysis / Q000379:methods*; D013455:Sulfur / Q000737:chemistry*; D014965:X-Rays
chemical_list: D001959:Bromates; D007202:Indicators and Reagents; D007452:Iodates; D017680:Potassium Compounds; C019536:potassium bromate; D013455:Sulfur; D005983:Glutens; C037302:glutenin; C039693:potassium iodate