PURIFICATION AND CHARACTERIZATION OF HIGH M(R) GLUTENIN SUBUNIT-20 AND ITS LINKED Y-TYPE SUBUNIT FROM DURUM-WHEAT

High M(r) glutenin subunit 20 and its linked y-type subunit, present i n the durum wheat cultivar Lira, were purified by preparative reversed -phase high-performance liquid chromatography (RP-HPLC). ;Imino acid a nd N-terminal sequence analysis of subunit 20y confirmed that it corre sponded 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 thar subunit 20 had only two cysteine residues, one in the N-terminal region and the o ther in the C-terminal domain. (C) 1996 Academic Press Limited