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영어
Lipase is a well-known enzyme and used as a biocatalyst for chemical and food processes and bio-diesel production. The calB gene coding for lipase B was cloned from the Candida antarctica ATCC32657 genomic DNA. Recombinant CalB fused with the 10 arginine (R10) or lysine (K10) tag at its C-terminal was expressed in Escherichia coli . SDS PAGE-analysis of CalB expression indicated that the band densities of soluble lipase B fused with R10 (CalB-R10) and K10
(CalB-K10) were 2.2 and 1.8 times higher than that of CalB without any tags, respectively. Activity assay of the crude protein extract using para-nitrophenyl palmitate as a substrate showed that CalB-R10 and CalB-K10 possessed 31.7±0.28 U/mg and 26.2±0.37 U/mg of specific activities, respectively, which were 1.5-1.9 times higher than that of CalB (17.1±0.6 U/mg). Incubation of the soluble CalB-R10 at pH9.0 and CalB-K10 at pH10.0 for 7 days resulted in 49%
and 45% decreases in specific activity, respectively, corresponding to a nearly 2-fold increase compared with specific CalB activity.