title: Identification and partial characterisation of a chitinase from Nile tilapia, Oreochromis niloticus.
abstract: Measurement of chitinase activity in extracts from stomach, intestine, and serum of Nile tilapia with the artificial substrates 4-methylumbelliferil beta-D-N,N'-diacetylchitobioside and 4-methylumbelliferil beta-D-N,N'N"-triacetylchitotrioside (4MU[GlcNAc](2,3)) showed that an endochitinase was involved in the liberation of the fluorophore 4-methylumbelliferone (MU). Enzymes were isolated from tilapia serum by a combination of gel filtration, ion exchange, and reverse-phase chromatography. The molecular mass of the enzyme was estimated to be 75 kDa by SDS-PAGE, suggesting that the enzyme occurs as a monomer. The partially purified enzyme showed maximal activity at pH 7.0 when assayed with 4MU[GlcNAc](2) and lost its activity below pH 5.0 and above pH 8.0. The optimal pH of the purified enzyme toward the substrate 4MU[GlcNAc](3) was pH 9.0 and activity was lost below pH 8.0 and above pH 9.0. Our study has revealed the presence of a chitinolytic enzyme in the gastrointestinal tract and serum that may play a role in digestion and/or defense.
authors.affiliation: Programa de Pós-Graduação em Microbiologia, Universidade Estadual de Londrina, Brazil.
authors.forename: Lígia Maria
authors.initials: LM
authors.lastname: Molinari
authors.forename: Raissa Bocchi
authors.initials: RB
authors.lastname: Pedroso
authors.forename: Denise de Oliveira
authors.initials: Dde O
authors.lastname: Scoaris
authors.forename: Tânia
authors.initials: T
authors.lastname: Ueda-Nakamura
authors.forename: Celso Vataru
authors.initials: CV
authors.lastname: Nakamura
authors.forename: Benedito Prado
authors.initials: BP
authors.lastname: Dias Filho
mesh_terms: D000818:Animals; D002688:Chitinases / Q000097:blood / Q000737:chemistry* / Q000302:isolation & purification; D023681:Cichlids / Q000097:blood*; D004789:Enzyme Activation / Q000502:physiology; D006863:Hydrogen-Ion Concentration; D007422:Intestines / Q000201:enzymology; D013270:Stomach / Q000201:enzymology; D013379:Substrate Specificity / Q000502:physiology
chemical_list: D002688:Chitinases