期刊
COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY B-BIOCHEMISTRY & MOLECULAR BIOLOGY
卷 146, 期 1, 页码 81-87出版社
ELSEVIER SCIENCE INC
DOI: 10.1016/j.cbpb.2006.09.004
关键词
chitin; chitinase; fish; Nile tilapia; Oreochromis niloticus; gastrointestinal tract; serum; HPLC
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-N,N',N-triacetylchitotrioside (4MU[GlcNAc](2,3)) showed that an endochitinase was involved in the liberation of the fluorophore 4-methylumbelliferone (MIJ). 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 4W [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. (c) 2006 Elsevier Inc. All rights reserved.
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