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.
KeywordsVasoactive Intestinal Peptide Gastric Inhibitory Polypeptide Jack Bean Protein Sequence Analysis Protein Protease Inhibitor
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