Authors: Xinhao Ye Zhiguang Zhu Chenming Zhang YH Percival Zhang
Publish Date: 2011/06/01
Volume: 92, Issue: 3, Pages: 551-560
Abstract
Clostridium thermocellum cellodextrin phosphorylase CtCDP a singlemodule protein without an apparent carbohydratebinding module has reported activities on soluble cellodextrin with a degree of polymerization DP from two to five In this study CtCDP was first discovered to have weak activities on weakly watersoluble celloheptaose and insoluble regenerated amorphous cellulose RAC To enhance its activity on solid cellulosic materials four cellulose binding modules eg CBM3 type A from C thermocellum CbhA CBM42 type B from Rhodothermus marinus Xyn10A CBM6 type B from Cellvibrio mixtus Cel5B and CBM92 type C from Thermotoga maritima Xyn10A were fused to the C terminus of CtCDP Fusion of any selected CBM with CtCDP did not influence its kinetic parameters on cellobiose but affected the binding and catalytic properties on celloheptaose and RAC differently Among them addition of CBM9 to CtCDP resulted in a 27fold increase of catalytic efficiency for degrading celloheptaose CtCDPCBM9 exhibited enhanced specific activities over 20 on the shortchain RAC DP = 14 and more than 50 on the longchain RAC DP = 164 The chimeric protein CtCDPCBM9 would be the first step to construct a cellulose phosphorylase for in vitro hydrogen production from cellulose by synthetic pathway biotransformation SyPaB
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