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KMID : 1094720180230010079
Biotechnology and Bioprocess Engineering
2018 Volume.23 No. 1 p.79 ~ p.85
Fusion of Carbohydrate Binding Modules to Bifunctional Cellulase to Enhance Binding Affinity and Cellulolytic Activity
Maharjan Anoth

Alkotaini Bassam
Kim Beom-Soo
Abstract
Bifunctional cellulase (glycoside hydrolase 5, GH5) from Bacillus sp. D04 having both endo- and exoglucanase activities was fused with two types of carbohydrate binding modules (CBMs). CBM3 from Bacillus sp. D04 and CBM9 from Thermotoga maritima Xyn10A were added to GH5 to hydrolyze microcrystalline cellulose (Avicel) as well as water-soluble cellulose (carboxymethyl cellulose, CMC). The optimum temperature of GH5 was 50oC, while it increased to 60oC for the fusion GH5-CBM3 and GH5-CBM9, indicating that addition of CBM increased the thermostability of the enzyme. Addition of CBM3 and CBM9 enhanced the GH5 affinity (KM), for which KM decreased from 104 to 33.9 ~ 35.1 mg/mL for CMC, and from 115 to 55.5 ~ 80.3 mg/mL for Avicel, respectively. The catalytic efficiency (kcat/KM) also increased from 4.80 to 5.36 ~ 6.46 (mL/mg)/sec for CMC, and from 1.77 to 2.40 ~ 4.45 (mL/mg)/sec for Avicel, respectively, by addition of CBM3 and CBM9.
KEYWORD
bifunctional cellulase, carbohydrate binding module, cellulose hydrolysis, fusion enzyme
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