SULFHYDRYL AND DISULFIDE GROUPS OF THE OLIGOMERIC SEED GLOBULIN FROM AMARANTHUS-HYPOCHONDRIACUS K343

The hetero-oligomeric seed globulin from amaranth was found to contain high levels of sulfhydryl and disulfide groups. Results suggested tha t the majority of sulfhydryl groups were buried deep within subunits o f this hetero-oligomer and were found to have varying degrees of react ivities. In the presence of N-ethylmaleimide (NEM), total alkylation o f sulfhydryl groups was not possible and was the probable reason for t he inability to completely inhibit polymerization of the globulin via a sulfhydryl-disulfide interchange mechanism. Disulfide linkages were important in stabilizing the protein and for the spontaneous dimerizat ion (following reduction) of certain subunits after elimination of the reductant. In addition, these disulfide linkages are thought to be im portant for maintenance of the quaternary structure of the globulin. L ittle change in the secondary structure of the globulin was shown to o ccur upon reduction.