title: Three extracellular chitinases in suspension-cultured rice cells elicited by N-acetylchitooligosaccharides.
abstract: In rice suspension culture, a large part (about 90% of total activity in the culture) of the chitinase activity was found in the medium. Two extracellular chitinases (which we named RCH-A and -B) were separated from the cell suspension by DEAE-cellulofine column chromatography. When cells were treated with N-acetylchitooligosaccharides (chitin oligosaccharides) for 3 days, extracellular chitinase activity increased about 3-fold over the control culture. After the treatment, another extracellular chitinase (named RCH-C) appeared in addition to increases in the levels of RCH-A and -B. Partial amino acid sequences of these enzymes indicated that RCH-A (33.5 kDa) and -B (34 kDa) were class Ib chitinases but RCH-C (27 kDa) was a class III chitinase. RCH-A and -B were capable of actively degrading water-insoluble chitin with high affinities, while RCH-C had less affinity for the substrate. However, when a water-soluble chitin derivative, 6-O-hydroxyethylchitin (glycolchitin) was used, RCH-C as well as RCH-A and -B degraded actively with a high affinity. A synergistic effect was observed when these three chitinases acted simultaneously in the hydrolysis of chitin.
authors.affiliation: Department of Agricultural Biochemistry and Biotechnology, Tottori University, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Inui
authors.forename: Y
authors.initials: Y
authors.lastname: Yamaguchi
authors.forename: Y
authors.initials: Y
authors.lastname: Ishigami
authors.forename: S
authors.initials: S
authors.lastname: Kawaguchi
authors.forename: T
authors.initials: T
authors.lastname: Yamada
authors.forename: H
authors.initials: H
authors.lastname: Ihara
authors.forename: S
authors.initials: S
authors.lastname: Hirano
mesh_terms: D000595:Amino Acid Sequence; D002384:Catalysis; D002478:Cells, Cultured; D002688:Chitinases / Q000096:biosynthesis* / Q000302:isolation & purification; D004591:Electrophoresis, Polyacrylamide Gel; D005110:Extracellular Space / Q000378:metabolism; D007700:Kinetics; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000494:pharmacology*; D012275:Oryza / Q000201:enzymology*
chemical_list: D009844:Oligosaccharides; D002688:Chitinases