Deciphering heterogeneous enzymatic surface reactions on xylan using surface plasmon resonance spectroscopy
Xylans’ unique properties make it attractive for a variety of industries, including paper, food, and biochemical production. While for some applications the preservation of its natural structure is crucial, for others the degradation into monosaccharides is essential. For the complete breakdown, the use of several enzymes is required, due to its structural complexity. In fact, the specificity of enzymatically-catalyzed reactions is guided by the surface, limiting or regulating accessibility and serving structurally encoded input guiding the actions of the enzymes. Here, we investigate enzymes at surfaces rich in xylan using surface plasmon resonance spectroscopy. The influence of diffusion and changes in substrate morphology is studied via enzyme surface kinetics simulations, yielding reaction rates and constants. We propose kinetic models, which can be applied to the degradation of multilayer biopolymer films. The most advanced model was verified by its successful application to the degradation of a thin film of polyhydroxybutyrate treated with a polyhydroxybutyrate-depolymerase. The herein derived models can be employed to quantify the degradation kinetics of various enzymes on biopolymers in heterogeneous environments, often prevalent in industrial processes. The identification of key factors influencing reaction rates such as inhibition will contribute to the quantification of intricate dynamics in complex systems.
1. Graz University of Technology, Institute of Bioproducts and Paper Technology (BPTI), Inffeldgasse 23, 8010 Graz, Austria
2. Graz University of Technology, Institute for Chemistry and Technology of Materials (ICTM), Stremayrgasse 9, 8010 Graz, Austria
3. Graz University of Technology, Institute of Molecular Biotechnology, Petersgasse 14, 8010 Graz, Austria
4. The COMET Center, Acib GmbH, Krenngasse 37, 8010 Graz, Austria
5. Chalmers University of Technology, Department of Life Sciences, 412 96 Gothenburg, Sweden
6. Chalmers University of Technology, Department of Chemistry and Chemical Engineering, 412 96 Gothenburg, Sweden
7. Aalto University, Department of Bioproducts and Biosystems, Vuorimiehentie 1, 02150 Espoo, Finland
* Corresponding author, Members of NAWI Graz and the European Polysaccharide Network of Excellence (EPNOE).