A Novel Protease from Jack-Bean Seeds: Asparaginyl Endopeptidase
Enzymatical and chemical reactions that induce the peptide-bond cleavage at definite amino acid residues and so produce a limited number of fragments from proteins are essential tools in protein sequence analysis. Although several kinds of residue-specific proteases are now widely used for this purpose, the asparaginyl-bond specific protease has not been available yet. Carrington et al. (1985) and Bowles et al. (1986) have reported that concanavalin A, a lectin of jack bean (Canavalia ensiformis), is produced by post-translational proteolysis and transpeptidation (or ligation) at the carboxyl side of Asn-residues of its precursor. Their results suggest that the bean at least in its premature state contains an asparaginyl endopeptidase which may have a dual function, proteolysis and transpeptidation. We confirmed this suggestion by isolating it from commercially available jack-bean meal and showed its high utility in protein sequence analysis. Purification and characterization of this novel protease are described in the following.
KeywordsCysteine Serine Polypeptide Trypsin Turkey
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