Polycaprolactone Enzymatic Hydrolysis: A Mechanistic Study

Accumulation of plastic waste is a major environmental problem. Enzymes, particularly esterases, play an important role in the biodegradation of polyesters. These enzymes are usually only active on aliphatic polyesters, but a few have showed catalytic activity for semi-aromatic polyesters. Because of the importance of these processes, an atomic-level characterization of how common polyesters are degraded by esterases is necessary. Hereby, we present a molecular dynamics (MD) and quantum mechanics/molecular mechanics MD study of the hydrolysis of a model of polycaprolactone, one of the most widely used biomaterials, by the thermophilic esterase from the archaeon Archaeoglobus fulgidus. This enzyme is particularly interesting because it can withstand temperatures well above the glass transition of many polyesters. Our insights about the reaction mechanism are important for the design of customized enzymes able to degrade different synthetic polyesters.