Purification and Characterisation of HighMrGlutenin Subunit 20 and its Linked y-type Subunit from Durum Wheat

HighM_rglutenin subunit 20 and its linked y-type subunit, present in the durum wheat cultivar Lira, were purified by preparative reversed-phase high-performance liquid chromatography (RP–HPLC). Amino acid and N-terminal sequence analysis of subunit 20y confirmed that it corresponded to a y-type subunit. Moreover, the number and position of the cysteine residues in subunit 20 were determined by alkylation with the fluorogenic reagent 7-fluoro-4-sulfamoyl-2,1,3,-benzoxadiazole (ABD-F) and subsequent enzymic digestion with trypsin. N-terminal amino acid sequence analysis of the fluorescent peptides showed that subunit 20 had only two cysteine residues, one in the N-terminal region and the other in the C-terminal domain.