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|Title:||Biochemical characterisation of two forms of halo- and thermo-tolerant chitinase C of Salinivibrio costicola expressed in Escherichia coli|
David W. Rice
University of Sheffield
|Keywords:||Immunology and Microbiology|
|Citation:||Annals of Microbiology. Vol.57, No.2 (2007), 249-257|
|Abstract:||Two forms of chitinase C (Chi-I and Chi-II) were purified until homogeneity from the culture supernatant of a transformant Escherichia coli harbouring chitinase C gene from the halophilic bacterium Salinivibrio costicola strain 5SM-1. Chi-II was derived from Chi-I by C-terminal processing. Chi-I and Chi-II showed similar salinity optimum at 1-2% NaCl and retained more than 80% of their activity at 3-5% NaCl and more than 50% residual activity at 14% NaCI. The two enzymes could also well function (activity > 95%) in the absence of NaCI. Both had highest activity at pH 7.0 and 50°C and both were stable over a wide range of pH (3.0-10.0). More than 50% activity remained at 80°C after 60 min treatment. Among 4 major cations contained in sea water, only Mg2+at 10 mM increased activity about 10%. Using ρ-nitrophenyl-N, N′-diacetylchitobiose as substrate, Chi-I and Chi-II had Kmof 30 and 31.8 μM and Vmaxof 10 and 9.2 pmol/h/mg protein, respectively. Chi-I and Chi-II were classified as exochitinases by product analysis of the E. coli culture supernatant with high performance liquid chromatography (HPLC) and thin-layer chromatography (TLC).|
|Appears in Collections:||Scopus 2006-2010|
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