کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
607800 1454601 2013 11 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Surface kinetics for cooperative fungal cellulase digestion of cellulose from quartz crystal microgravimetry
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی شیمی کلوئیدی و سطحی
پیش نمایش صفحه اول مقاله
Surface kinetics for cooperative fungal cellulase digestion of cellulose from quartz crystal microgravimetry
چکیده انگلیسی

The kinetic behavior of aqueous cellulase on insoluble cellulose is best quantified through surface-based assays on a well-defined cellulose substrate of known area. We use a quartz crystal microbalance (QCM) to measure the activity of binary mixtures of Trichoderma longibrachiatum cellobiohydrolase I (Cel7A) and endoglucanase I (Cel7B) on spin-coated cellulose films. By extending a previous surface kinetic model for cellulase activity, we obtain rate constants for competitive adsorption of Cel7A and Cel7B, their irreversible binding, their complexation with the cellulose surface, and their cooperative cellulolytic activity. The activity of the two cellulases is linked through the formation of cellulose chain ends by Cel7B that provide complexation sites from which Cel7A effects cellulose chain scission. Although the rate-limiting step in Cel7A activity is complexation, Cel7B activity is limited by adsorption to the cellulose surface. A 2:1 bulk mass ratio of aqueous Cel7A:Cel7B, corresponding to a 4:1 surface mass ratio, effects the greatest rate of cellulose degradation across a range of cellulase concentrations at 25 °C. We find that surface chain-end concentration is a major predictor of Cel7A activity. Disruption of the hydrogen-bonding structure of cellulose by Cel7B enhances the activity of Cel7A on the cellulose surface.

Figure optionsDownload high-quality image (40 K)Download as PowerPoint slideHighlights
► Quartz crystal microbalance used to quantify action of cellulases on a cellulose film.
► Kinetic parameters are determined for adsorption and activity of Cel7A and Cel7B.
► New kinetic model uses these parameters to describe cooperativity of Cel7A and Cel7B.
► Optimal Cel7A:Cel7B bulk ratio of 2:1 determined from kinetic model.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Colloid and Interface Science - Volume 394, 15 March 2013, Pages 498–508
نویسندگان
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