Masanori Mitta

The nucleotide sequence of human aminoacylase-1

The nucleotide sequence of a cDNA coding for human aminoacylase-1 (N-acylamino acid aminohydrolase, ACY-1, EC 3.5.1.14) subunit has been determined. The amino acid sequence of human ACY-1 subunit deduced from its cDNA nucleotide sequence showed a high degree of identity (87.7%) with the corresponding protein from porcine [1], although the former is one amino acid residue longer than the latter. Of 12 histidine and 3 cysteine residues, conserved between the proteins from two species, some are anticipated to form the active site of ACY-1 as either catalytic residues or ligands for an essential Zn2+ atom.

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.