Biochemical properties
Polyurethanes comprise numerous possible polymers of diverse composition, such as combinations of different isocyanates with different polyethers, polyesters, or polycarbonates41. The best studied PURases are α/β-hydrolases, as reviewed in more detail in 41. Only ten characterized PUR-degrading enzymes (PURases) have been reported, yet. Four recently identified enzymes (LCC, TfCut-2, Tcur_1278 T, and Tcur0390) are cutinases from Actinomyces, which are also active on PET and have a broad substrate profile42. Further bacterial lipases from Betaproteobacteria have been identified and characterized, such asPueA and PueB from Pseudomonas chlororaphis.Whereas all the above-mentioned studies identified lipases or esterases, earlier studies reported that commercially available peptidases and proteases might also degrade thin PUR films 43.