Triton X-100 modified polygalacturonic acid: A novel coating for enhanced activity of immobilized lipases

Lipases are commonly immobilized covalently on agarose supports to improve their stability and reusability. However, immobilized lipases often have low activity in aqueous environments since they are typically immobilized with the lid domain covering the active site (i.e. in the closed conformation), restricting the access of substrates. The nonionic surfactant Triton X-100 (TX-100) facilitates the opening of the lid and access of the substrate. However, the addition of TX-100 in its free form leads to foaming problems and contamination of the final product, hindering industrial applications. In this work, we functionalize polygalacturonic acid (PGA) with TX-100 and use it as a novel agent for coating the immobilized lipase from Thermomyces lanuginosus (TLL). This coating stabilizes the lid of TLL in the open conformation, improving catalytic performance, avoiding the need to add free surfactants. The specific activities of the coated immobilized lipases for the hydrolysis of p-nitrophenyl propionate (p-NPP) were 3- to 5-fold higher than that of the uncoated lipase, and were similar to that of the free TLL in the presence of free TX-100. These findings show that coating with PGA-TX is an effective strategy for enhancing lipase activity, offering a promising alternative to conventional surfactant-based activation.