Purification and characterization of two Kunitz family subtilisin inhibitors from seeds of Canavalia lineata.
Two subtilisin inhibitors (CLSI-II and -III) were purified from seeds of Canavalia lineata by extraction with water, ammonium sulfate precipitation, and chromatographies on DEAE-Toyopearl and hydroxyapatite. The two inhibitors have the same molecular weight of about 22,000, and quite similar amino acid compositions. They contain five half-cystine residues and tend to dimerize through an intermolecular disulfide bridge due to the presence of a single cysteine residue. CLSI-III only inhibited subtilisin-type serine proteases, while CLSI-II showed a wider inhibitory specificity. Though the two inhibitors have almost identical thermal labilities, CLSI-II is more stable as to extreme pH than CLSI-III. They are considered to be Kunitz type inhibitors on the basis of several properties.
Terada
S
S
Department of Chemistry, Faculty of Science, Fukuoka University.
Fujimura
S
S
Katayama
H
H
Nagasawa
M
M
Kimoto
E
E
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D002852:Chromatography, Ion Exchange; D004591:Electrophoresis, Polyacrylamide Gel; D007887:Fabaceae / Q000737:chemistry*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010940:Plant Proteins / Q000737:chemistry* / Q000302:isolation & purification* / Q000494:pharmacology; D010946:Plants, Medicinal; D012639:Seeds / Q000737:chemistry*; D013381:Subtilisins / Q000037:antagonists & inhibitors*
D000596:Amino Acids; C088838:CLSI protein, Canavalia lineata; D010940:Plant Proteins; D013381:Subtilisins