Disulphide bonds of adjacent cysteine residues in low molecular weight subunits of wheat glutenin
1998
Muller, S. | Vensel, W.H. | Kasarda, D.D. | Kohler, P. | Wieser, H.
The adjacent cysteine residues C(f1) and C(f2) located in the homologous sequence division III of LMW subunits of glutenin, and of alpha- and gamma-gliadins are important elements of the disulphide structure of these proteins. Two different analytical approaches were used to assign the disulphide linkages of the -Cys-Cys- sequence found in four cystine-containing peptides derived from LMW subunits of glutenin. Direct Edman degradation of the acetylated and cyanogen bromide treated peptide with detection of di-PTH-cystine was one method. Partial reduction of peptides with Tris(2-carboxyethyl)-phosphine hydrochloride, subsequent separation of fragments by RP-HPLC, alkylation with iodoacetamide and sequence analysis was the second method. Both these methodologies gave identical results. It was shown that the first of the adjacent cysteines (C(f1)) is linked with another cysteine residue of division III (C(c)) and that the second one of the pair (C(f2)) is linked with a cysteine residue in the C-terminal division V (C(y)) of the primary structure. A model for the complete disulphide structure of LMW subunits is presented.
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