title: Characterisation of a chitinase from Pseudoalteromonas sp. DL-6, a marine psychrophilic bacterium.
abstract: In this study, we isolated a new psychrophilic bacterium, Pseudoalteromonas sp. DL-6 from marine sediments, which grew well on chitin-containing plates at 4°C. One endo-type chitinase gene, chiA, was cloned from the genomic DNA of this bacterium and heterologously expressed in Escherichia coli BL21 (DE3). ChiA showed very high catalytic activity, even at 4°C, and exhibited maximal activity on a chitinous substrate at pH 8.0 and 20°C. Kinetic studies indicated that ChiA has a greater catalytic efficiency on 4-methylumbelliferyl-β-D-N,N',N″-triacetylchitotriose[4-MU(GlcNAc)3] than on 4-methylumbelliferyl-β-D-N,N'-diacetylchitobioside[4-MU(GlcNAc)2]. Electrospray ionisation mass spectrometry (ESI-MS) analysis showed that the hydrolysis products of powdered chitin after ChiA digestion consisted of a series of chitin oligomers with different degrees of polymerisation. The ChiA mode of action was also examined using (GlcNAc)2-6 as a substrate, and the results suggested that ChiA is a non-processive endo-type chitinase.
authors: Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China; School of Life Science and Biotechnology, Dalian University, Dalian 116622, China; School of Life Science and Biotechnology, Dalian University of Technology, Dalian 116024, China; University of Chinese Academy of Sciences, Beijing 100049, China.
authors: Xiaohui
authors: X
authors: Wang
authors: Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
authors: Yong
authors: Y
authors: Zhao
authors: Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
authors: Haidong
authors: H
authors: Tan
authors: School of Life Science and Biotechnology, Dalian University, Dalian 116622, China.
authors: Naiyu
authors: N
authors: Chi
authors: School of Life Science and Biotechnology, Dalian University, Dalian 116622, China.
authors: Qingfang
authors: Q
authors: Zhang
authors: Institute of Process Engineering, Chinese Academy of Science, Beijing 100190, China.
authors: Yuguang
authors: Y
authors: Du
authors: Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China. Electronic address: yinheng@dicp.ac.cn.
authors: Heng
authors: H
authors: Yin
mesh_terms: D002686:Chitin / Q000378:metabolism; D002688:Chitinases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D004789:Enzyme Activation; D015870:Gene Expression; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D031161:Pseudoalteromonas / Q000145:classification / Q000201:enzymology* / Q000235:genetics; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D002686:Chitin; D002688:Chitinases
keywords: Characterisation; Chitinase; Purification