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Study and design of stability in GH5 cellulases

Authors

  • Somayesadat Badieyan,

    1. Department of Biological Systems Engineering, Virginia Polytechnic Institute and State University, Blacksburg, Virginia, 24061; telephone: 540-231-7601; fax: 540-231-3199
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  • David R. Bevan,

    Corresponding author
    1. Department of Biochemistry, Virginia Polytechnic Institute and State University, Blacksburg, Virginia, 24061; telephone: 540-231-5040
    • Department of Biochemistry, Virginia Polytechnic Institute and State University, Blacksburg, Virginia, 24061; telephone: 540-231-5040.
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    • Associate Professor.

  • Chenming Zhang

    Corresponding author
    1. Department of Biological Systems Engineering, Virginia Polytechnic Institute and State University, Blacksburg, Virginia, 24061; telephone: 540-231-7601; fax: 540-231-3199
    • Department of Biological Systems Engineering, Virginia Polytechnic Institute and State University, Blacksburg, Virginia, 24061; telephone: 540-231-7601; fax: 540-231-3199.
    Search for more papers by this author
    • Associate Professor.


Abstract

Thermostable enzymes that hydrolyze lignocellulosic materials provide potential advantages in process configuration and enhancement of production efficiency over their mesophilic counterparts in the bioethanol industry. In this study, the dynamics of β-1,4-endoglucanases (EC: 3.2.1.4) from family 5 of glycoside hydrolases (GH5) were investigated computationally. The conformational flexibility of 12 GH5 cellulases, ranging from psychrophilic to hyperthermophilic, was investigated by molecular dynamics (MD) simulations at elevated temperatures. The results indicated that the protein flexibility and optimum activity temperatures are appreciably correlated. Intra-protein interactions, packing density and solvent accessible area were further examined in crystal structures to investigate factors that are possibly involved in higher rigidity of thermostable cellulases. The MD simulations and the rules learned from analyses of stabilizing factors were used in design of mutations toward the thermostabilization of cellulase C, one of the GH5 endoglucanases. This enzyme was successfully stabilized both chemically and thermally by introduction of a new disulfide cross-link to its highly mobile 56-amino acid subdomain. Biotechnol. Bioeng. 2012;109: 31–44. © 2011 Wiley Periodicals, Inc.

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