Plant-derived polymers including cellulose, hemicellulose and lignin could be chemically and/or enzymatically engineered to obtain new functional properties and create high-value products. Therefore, methods to detect binding interactions as well as enzymatic activities on these high molecular-weight, plant-derived materials have been developed.
In particular, these plant polymers were coated on Quartz Crystal Microbalance with Dissipation Monitoring (QCM-D) sensors, allowing us to measure the binding of CAZymes and degradation of these polymeric surfaces. QCM-D procedures were also established in our laboratory to unveil mass contribution of water in these binding interactions, and to quantify rates of adsorption and desorption, facilitating data comparison.
Lytic polysaccharide monooxygenases (LPMOs) are increasingly important for biomass degradation and modification. Two surface analysis techniques including X-ray Photoelectron Spectroscopy (XPS) and Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) were employed. XPS has demonstrated to be sufficiently sensitive to detect the activity of LPMOs on cellulose samples. ToF-SIMS is being optimized, as it would also allow detecting the activity of other enzymes directly on wood. Additionally, a fluorescent, microplate-based assay was developed for screening activity of LPMOs on cellulose by covalently linking fluorophores to oxidized positions. All of these methods provide useful tools to discover CAZymes acting on polymeric substrates as well as plant/tree powders.
Dr. Thu Vuong