Purification and characterization of two chitinase isoforms from the bulbs of gladiolus (Gladiolus gandavensis).
Two chitinase isoforms, designated GBC-a and GBC-b, were purified from the bulbs of gladiolus (Gladiolus gandavensis) using CM-cellulose column chromatography followed by Butyl-Toyopearl 650 M hydrophobic column chromatography, gel filtration on Sephadex G-75, and Mono-S FPLC. GBC-a and GBC-b are weakly acidic and weakly basic proteins with molecular masses of 30 kDa, and isoelectric points of 6.0 and 7.5, respectively. GBC-a and GBC-b were found to be homologous proteins with similar amino acid compositions and N-terminal sequences. The number of half-cystine residues in GBC-a and GBC-b was only one each, which is much lower than those of plant class I (15-17 Cys residues/mol), class II (5-8 Cys residues/mol), and class III (6 Cys residues/mol) chitinases. The N-terminal sequences of GBC-a and GBC-b were completely different from those of plant three classes of chitinases. The optimal pHs of these chitinases toward glycolchitin were pH 5. GBC-a hydrolyzed (GlcNAc)5 into (GlcNAc)2, (GlcNAc)3 and (GlcNAc)4, and (GlcNAc)5 into (GlcNAc)2 and (GlcNAc)3.
Yamagami
T
T
Laboratory of Protein Chemistry & Engineering, Faculty of Agriculture, Kyushu University, Fukuoka, Japan. yamagami@agr.kyushu-u.ac.jp
Mine
Y
Y
Aso
Y
Y
Ishiguro
M
M
D000595:Amino Acid Sequence; D002686:Chitin / Q000031:analogs & derivatives / Q000737:chemistry; D002688:Chitinases / Q000302:isolation & purification*; D007527:Isoenzymes / Q000302:isolation & purification*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D018517:Plant Roots / Q000201:enzymology; D010944:Plants / Q000201:enzymology*
D007527:Isoenzymes; D002686:Chitin; C031610:glycolchitin; D002688:Chitinases