Ring-opening polymerization of ɛ-caprolactone catalyzed by a novel thermophilic lipase from Fervidobacterium nodosum

The paper explored the catalytic activity of a novel thermophilic lipase from Fervidobacterium nodosum for polyester synthesis, using the ring-opening polymerization of ɛ-caprolactone as the model. Effects of enzyme concentration, reaction medium, temperature and reaction time on monomer conversion, product molecular weight and distribution were systematically investigated. Remarkably, the enzyme could be effectively performed at high temperatures, and showed the highest activity towards the polymerization of ɛ-caprolactone at 90 °C. Through the optimization of reaction conditions, poly(ɛ-caprolactone) was obtained in almost 100% monomer conversion, with a number-average molecular weight of 2340 g/mol and a polydispersity index of 1.34 in toluene at 90 °C for 72 h. Michaelis–Menten kinetic analysis indicated that compared with Candida antarctica lipase B, the enzyme had higher affinity for ɛ-caprolactone with a Km value of 0.35 mol/L. Furthermore, the possible structural and energetic basis of the interaction of enzyme and the monomer ɛ-caprolactone was elucidated using molecular docking.