CONTROLLED REDUCTION STUDY OF MODIFICATIONS INDUCED BY GRADUAL HEATING IN GLUTEN PROTEINS

The stepwise Seduction with dithiothreitol (DTT) of proteins in native and heat-treated gluten (1 h, 45-110 degrees C) was studied by SDS-PA GE. In native gluten and after heating at 45 degrees C, up to 0.02 mM DTT led to no apparent change. Subunits from glutenins and high-molecu lar weight (HMW) albumins were released with 0.4-10 mM DTT, indicating the presence of disulfide bonds with different susceptibilities to re duction. Monomeric proteins were more resistant to reduction; low-mole cular weight (LMW) albumins/globulins were reduced at 2 mM DTT and alp ha- and gamma-type gliadins at 4 mM DTT. At 65 degrees C, only the HMW albumins were affected; they lost water solubility and amylase activi ty and were released at higher DTT concentrations. When heated above 9 0 degrees C, all the proteins, except the omega-gliadins, formed disul fide-bonded aggregates. The supposed D glutenin subunits were released at 0.4 mM DTT, the HMW glutenin subunits at 2 mM DTT, and the other p roteins at 4 mM DTT. Gluten proteins therefore appeared to be involved differently in heat-induced aggregation.