Cereal Chem 55:16 - 22.  |  VIEW ARTICLE
Disulfide and Sulfhydryl Groups in Glycinin.

M. Draper and N. Catsimpoolas. Copyright 1978 by the American Association of Cereal Chemists, Inc. 

The number of disulfide (SS) bonds in glycinin and their rate of cleavage by dithiothreitol were determined at various concentrations of urea. A progressive increase in SS bond scission was observed with increasing urea concentration, reaching the maximum of 20 SS bonds at 8M urea. In addition, a linear relationship was obtained for the rate of SS cleavage as a function of urea concentration. These results indicate that most of the SS bridges are buried in the interior of the protein molecule. On exposure to alkaline denaturation, a maximum of 9.2 sulfhydryl (SH) groups were obtained per mole of glycinin at pH 11.9. Since glycinin in 6M urea contains only 1.7 SH groups per mole, the remaining SH groups are probably the result of the alkaline cleavage of some susceptible SS bonds.