ABSTRACT
Variation in power and time of sonication of gluten and glutenin suspensions was used to gain information about the mechanism of molecular breakdown. At low power, an increase in sulfhydryl (SH) content of solubilized gluten could be ascribed to additional glutenin brought into the solution. Higher power sonication of gluten suspensions, at constant protein concentration and with increasing times, progressively shifted the molecular weight distribution (measured by size exclusion HPLC) to lower molecular weights. It was accompanied by a parallel decrease in SH content. This suggested that the freed cysteine residues formed by scission of disulfide (SS) bonds, caused by sonication, reacted to form new intramolecular SS bonds with free cysteines on the same molecular fragments. Circular dichroism measurements appeared to support this conclusion. High-power ultrasound produced SE-HPLC profiles with diffuse peaks corresponding to HMW-GS and LMW-GS. SDS-PAGE patterns of protein fractions obtained in different elution ranges of SEHPLC confirmed that individual subunits had been produced by sonication. A fraction of the polymeric protein eluting at the void volume of SE-HPLC appeared to be resistant to breakdown by sonication.
