Towards structural and functional characterization of putative polyurethane degrading enzymes

Plastic pollution is a major environmental problem caused by the accumulation of plastic waste in the natural environment. The global production of plastic has increased rapidly over the past few decades, with 380 million tonnes per annum [1]. Around 70% of global production is concentrated in six major polymer types, the so-called commodity plastics [2]. These materials are inexpensive, versatile, and easy to work with, making them the preferred choice for the mass production of everyday objects. Our research is particularly focused on polyurethane (PUR) that is considered an adaptable material and can be found a wide range of applications, including insulation, adhesives, coatings, and foams [3]. The poor degradability of this material brought the scientific community in finding new solutions to harness the problem and, as in many other cases, enzymes revealed to be the leading players in this challenge. Framed in this context, in our research we are focused on finding enzyme candidates capable of degrading polyurethane fragments specifically attacking the urethane bond intrinsic of the polymer chemical structure. Among the copious amount of enzyme classes, Amidases [4], [5] caught our attention since their reaction with polyurethane would produce two fragments being a carbonyl and an amine moiety that could be recycled as valuable building blocks.