Changes in electrophoretic patterns of acetic acid-insoluble wheat flour proteins during dough mixing

Abstract

Acetic acid-insoluble (residue) protein fractions of wheat flours and respective doughs were studied by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS—PAGE). Gel patterns of unreduced SDS buffer extracts from residue fractions showed that dough mixing caused systematic changes in the staining intensity of a group of relatively high molecular weight proteins comprising triplet band proteins and neighboring bands. Together, these proteins were named in this study the triplet zone proteins. Continued mixing of control doughs resulted in a progressive decrease in the intensity of the triplet zone bands, whereas mixing in the presence of potassium iodate (KIO 3 ) and N -ethylmaleimide (NEMI) caused an increase in staining intensity of these bands. These results appear to be related to sulfhydryl-disulfide interchange reactions that have been proposed to occur during dough mixing. Results for doughs from water-extracted flour suggested water soluble components of the flour interacted during mixing with the triplet zone proteins. SDS—PAGE patterns of reduced proteins that could not enter the separating gel under non-reducing conditions (slot protein) resembled the patterns of purified glutenin. Electrophoretic patterns of slot protein of SDS buffer extracts from acetic acid-insoluble residues showed the presence of subunits that corresponded in molecular weight to subunits of triplet band proteins. This suggested the possibility of strong interaction between triplet band proteins and SDS-buffer extractable glutenin in flour and dough residues.