Molecular Analysis of Polymeric Glutenins in Wheat Gluten with Gliadin-like Characteristics by Ammonia Dispersion

Abstract

Wheat gluten prepared by dispersion in the presence of ammonia has unique dough properties similar to those of gliadin. In the present study, the mechanism of expression of these gliadin-like characteristics was investigated. In prolonged stirring with ammonia treatment, gluten gained even less elasticity, as shown by the marked decrease of dough resistance and bandwidth. Size-exclusion HPLC analysis showed that large-molecular sized polymeric glutenins decreased, but small-molecular sized polymeric glutenins increased with increases in ammonia dispersion time. SDS-PAGE of proteins labeled with monobromobimane revealed that the content of free sulfhydryl groups in the D-type of low-molecular weight glutenin subunits (LMW-GS) significantly decreased in ammonia-treated gluten to 56% of that in control gluten. We propose that during ammonia dispersion, free sulfhydryl groups in the D-type of LMW-GS attack the disulfide bonds in large polymeric glutenins and consequently, new small polymeric glutenins are generated by disulfide-sulfhydryl exchange reactions.