Cysteine-containing peptides are produced by sequential clipping, but not released, from lupin 11S storage globulin during early germination

The digestion of the seed storage proteins is a finely regulated process operated by several proteases whose action is influenced by the exposure of specific regions, which became progressively available upon their action. We focused our study on the initial stages of germination, where more subtle modifications to the storage proteins are expected. Small-size peptides containing cysteine residues and other possible metalbinding regions are de facto produced but are not released from the “parental” protein since they remain bound trough disulphide bridges. The meaning of these findings is discussed.