The utilization of wood-derived building blocks (xylochemicals) to replace fossil-based precursors is an attractive research subject of modern polymer science. Here, we demonstrate that bisguaiacol (BG), a lignin-derived bisphenol analogue, can be used to prepare biobased polyesters with remarkable thermal properties. BG was treated with different activated diacids to investigate the effect of co-monomer structures on the physical properties of the products. Namely, derivatives of adipic acid, succinic acid, and 2,5-furandicarboxylic acid were used. Moreover, a terephthalic acid derivative was used for comparison purposes. The products were characterized by H NMR spectroscopy, attenuated total reflectance FTIR spectroscopy, gel-permeation chromatography, thermogravimetric analysis, and differential scanning calorimetry to assess their structural and thermal properties in detail. The polymers showed glass-transition temperatures ranging up to 160 °C and thermal stabilities in excess of 300 °C. Furthermore, the susceptibility of the polyester to enzymatic hydrolysis was investigated to assess the potential for further surface functionalization and/or recycling and biodegradation. Indeed, hydrolysis with two different enzymes from the bacteria Thermobifida cellulosilytica led to the release of monomers, as quantified by HPLC. The results of this study indicate that our new polyesters represent promising renewable and biodegradable alternatives to petroleum-based polyesters currently employed in the plastics industry, specifically for applications in which high-temperature stability is essential to ensure overall system integrity.
Tyrosinases catalyse both the cresolase and catecholase reactions for the formation of reactive compounds which are very important for industrial applications. In this study, we describe a proteolytic activity of tyrosinases. Two different tyrosinases originating from mushroom and apple are able to cleave the carboxylesterase EstA. The cleavage reaction correlates with the integrity of the active site of tyrosinase and is independent of other possible influencing factors, which could be present in the reaction. Therefore, the cleavage of EstA represents a novel functionality of tyrosinases. EstA was previously reported to degrade synthetic polyesters, albeit slowly. However, the EstA truncated by tyrosinase shows higher degradation activity on the non-biodegradable polyester polyethylene terephthalate (PET), which is a well-established environmental threat.
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