Enzymatic catalysis in a whey protein matrix at temperatures in the vicinity of the glass transition |
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| Affiliation: | 1. Department of Chemistry, Moscow State University, Leninskie Gory, House 1, Building 3, GSP-2, Moscow 119991, Russia;2. Faculty of Materials Science, Moscow State University, Leninskie Gory, House 1, Building 73, GSP-1, Moscow 119991, Russia;3. Department of Petrology, Geological Faculty Moscow State University, Leninskie Gory, Moscow 119992, Russia;4. Department of Chemistry and Chemical Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4M1;5. Jiangsu Key Laboratory of Micro and Nano Heat Fluid Flow Technology and Energy Application, School of Mathematics and Physics, Suzhou University of Science and Technology, Suzhou 215009, China;6. Indian Institute of Technology Madras, Chennai 600036, India;7. Departamento de Física, Universidade Federal do Rio Grande do Norte, Natal 59082-970, Brazil;1. State Key Laboratory of Coordinate Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China;2. Grupo de Polímeros USB, Departamento de Ciencia de los Materiales, Universidad Simón Bolívar, Apartado 89000, Caracas 1080-A, Venezuela;3. POLYMAT and Polymer Science and Technology Department, Faculty of Chemistry, University of the Basque Country (UPV-EHU), Paseo Manuel de Lardizabal 3, 20018 Donostia-San Sebastián, Spain;4. IKERBASQUE, Basque Foundation for Science, Bilbao, Spain;5. Department of Chemistry, Tulane University, 6400 Freret St., New Orleans, LA 70118, USA;1. Analytical Chemistry Division, Department of Chemistry, Lomonosov Moscow State University, Leninskie Gory 1, bd. 3, Moscow 119991, GSP-1, Russia;2. Department of Materials Science and Engineering, Graduate School of Engineering, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan;3. Department of Chemical Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK;1. Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Wadden Sea Research Station, Hafenstraße 43, 25992 List/Sylt, Germany;2. Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Am Handelshafen 12, 27510 Bremerhaven, Germany;3. Helmholtz Centre Geesthacht, Institute of Coastal Research, Max-Planck-Straße 1, 21502 Geesthacht, Germany;4. Geologisch-Paläontologisches Institut der Universität Hamburg, Bundesstr. 55, 20146 Hamburg, Germany |
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| Abstract: | The current study evaluates the effect of temperature on α-glucosidase activity, following incorporation of the enzyme into a whey protein matrix through spray drying. Thermomechanical characterization of the matrix was achieved using the techniques of modulated temperature differential scanning calorimetry and small-deformation dynamic mechanical analysis. As the concentration was raised from 75 to 94% (w/w), denaturation of the protein occurred at increasing temperatures. In contrast, denaturation was not observed in calorimetric scans after spray drying. The glass transition temperature (Tg) measured in the dried particles using dynamic mechanical analysis was approximately 40 °C. An optimized procedure was developed whereby α-glucosidase and its substrate p-nitrophenyl α-d-glucopyranoside were incorporated into the whey matrix. The effect of temperature on enzymatic catalysis was investigated and, below 40 °C, activity was low and relatively independent of temperature. However, the rates of product formation markedly accelerated as temperatures were increased beyond Tg. These novel observations strongly emphasize the pronounced effect of mechanical Tg of the protein matrix on enzymatic activity. |
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