Amino acid sequences of Kunitz family subtilisin inhibitors from seeds of Canavalia lineata.
The amino acid sequences of two subtilisin inhibitors (CLSI-II and -III) from Canavalia lineata seeds were determined by manual Edman degradation using the DABITC/PITC double coupling method after enzymatic digestions and CNBr degradation. CLSI-II and -III consist of 190 and 183 amino acids, respectively, and have identical amino acid sequences except for in the C-terminal regions: an elongated sequence, Gly-Thr-Ile-Arg- Ser-Asp-Gly, was found at the C-terminus of CLSI-II. A short-chain analog protein without an N-terminal Asn residue was also detected in each inhibitor preparation. The inhibitors showed significant homology to Kunitz type inhibitors, but differed from them with respect to the half-cystine content. Among five half-cystine residues present in CLSI-III, two disulfide bonds link Cys44 to Cys88 and Cys142 to Cys149, Cys106 being present as a free cysteine residue. Phenylglyoxal treatment abolished the inhibitory activity of CLSI-III, indicating the participation of an Arg residue in the interaction with the enzyme. The reactive-site peptide bond was deduced to be Arg68-Gly69.
Terada
S
S
Department of Chemistry, Faculty of Science, Fukuoka University.
Katayama
H
H
Noda
K
K
Fujimura
S
S
Kimoto
E
E
D000595:Amino Acid Sequence; D001120:Arginine / Q000737:chemistry; D001665:Binding Sites; D005591:Chemical Fractionation; D002851:Chromatography, High Pressure Liquid; D003545:Cysteine / Q000737:chemistry; D007887:Fabaceae / Q000737:chemistry*; D005998:Glycine / Q000737:chemistry; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000737:chemistry* / Q000378:metabolism; D010946:Plants, Medicinal; D012639:Seeds / Q000737:chemistry*; D017386:Sequence Homology, Amino Acid; D013381:Subtilisins / Q000037:antagonists & inhibitors*
C088838:CLSI protein, Canavalia lineata; D010940:Plant Proteins; D001120:Arginine; D013381:Subtilisins; D003545:Cysteine; D005998:Glycine