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Rapid chromatography for evaluating adsorption characteristics of cellulase binding domain mimetics

Authors

  • Nathan S. Mosier,

    1. Department of Agricultural and Biological Engineering, 500 Central Drive, Purdue University, West Lafayette, Indiana 47907, USA; telephone: 765-494-7022; fax: 765-494-7023
    2. Laboratory of Renewable Resources Engineering, 500 Central Drive, Purdue University, West Lafayette, Indiana 47907, USA
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  • Jonathan J. Wilker,

    1. Department of Chemistry, 500 Central Drive, Purdue University, West Lafayette, Indiana 47907, USA
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  • Michael R. Ladisch

    1. Department of Agricultural and Biological Engineering, 500 Central Drive, Purdue University, West Lafayette, Indiana 47907, USA; telephone: 765-494-7022; fax: 765-494-7023
    2. Laboratory of Renewable Resources Engineering, 500 Central Drive, Purdue University, West Lafayette, Indiana 47907, USA
    3. Department of Biomedical Engineering, 500 Central Drive, Purdue University, West Lafayette, Indiana 47907, USA
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Abstract

The cost of cellulolytic enzymes is one barrier to the economic production of fermentable sugars from lignocellulosic biomass for the production of fuels and chemicals. One functional characteristic of cellulolytic enzymes that improves reaction kinetics over mineral acids is a cellulose binding domain that concentrates the catalytic domain to the substrate surface. We have identified maleic acid as an attractive catalytic domain with pKa and dicarboxylic acid structure properties that hydrolyze cellulose while producing minimal degradation of the glucose formed. In this study we report results of a rapid chromatographic method to assess the binding characteristics of potential cellulose binding domains for the construction of a synthetic cellulase over a wide range of temperatures (20° to 120°C). Aromatic, planar chemical structures appear to be key indicators of cellulose adsorption. Indole, the side-chain of the amino acid tryptophan, has been shown to reversibly adsorb to cellulose at temperatures between 30° and 120°C. Trypan blue, a polyaromatic, planar molecule, was shown to be irreversibly adsorbed to cotton cellulose at temperatures of <120°C on the time scale of the experiments. These results confirm the importance of hydrophobic cellulose and the cellulose-binding component of cellulolytic enzymes and cellulolytic enzyme mimetics. © 2004 Wiley Periodicals, Inc.

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