Effect of chemical modification on the binding of gossypol by gossypin (11S protein) and congossypin (7S protein) of cottonseed.

Binding of gossypol by gossypin and congossypin and their succinylated and
sulfhydryl group-blocked derivatives has been measured. The binding by gossypin and
congossypin is characterized by weak interaction. Succinylation of gossypin decreases the
binding affinity whereas that of congossypin increases it. Blocking of sulfhydryl groups of
both the proteins does not significantly affect gossypol binding, Succinylation dissociates
gossypin and causes conformational changes whereas it does not dissociate congossypin but
causes conformational changes. Sulfhydryl group blocking does not dissociate gossypin or
congossypin, nor does it cause any conformational changes.