Cereal Chem 62:279-283   |  VIEW ARTICLE
Selective Reduction of Interpolypeptide and Intrapolypeptide Disulfide Bonds of Wheat Glutenin from Defatted Flour.

Y. Kawamura, Y. Matsumura, T. Matoba, D. Yonezawa, and M. Kito. Copyright 1985 by the American Association of Cereal Chemists, Inc. 

Selective cleavage of interpolypeptide (intersubunit) SS bonds of wheat glutenin was accomplished by treatment with 32 mM 2-mercaptoethanol (2-ME) at pH 4.0 and 20 C for 4 hr. The subunits liberated by this partial reduction had uncleaved intrapolypeptide SS bonds, according to the following criteria: 1) Relative mobility on sodium dodecyl sulfate polyacrylamide gel electrophoresis of the subunits with low molecular weight from partial reduced glutenin was greater than that from the completely reduced glutenin, showing the compact conformation of subunits by uncleaved intrapolypeptide SS bonds. 2) With further reduction by 2-ME in the presence of 8M urea, these bands descreased their mobility and shifted to the position of the completely reduced glutenin subunits, indicating complete unfolding and expansion of the subunit polypeptides that may cause the decrease of electrophoretic mobility. The amount of cysteine residue involved in interpolypeptide and intrapolypeptide SS bonds was determined by selective modification with iodoacetamide and vinylpyridine respectively. All subunits contained 2 moles of interpolypeptide SS bonds per mole of subunit, whereas the number of intrapolypeptide SS bonds was 2-3 moles per mole of subunit. Wheat glutenin may be a linear polymer protein consisting of several subunits that link together through SS bonds.