Encapsulation of lipases by nucleotide/metal ion coordination polymers: enzymatic properties and their applications in glycerolysis and esterification studies

Abstract

BACKGROUND In the present study, lipases of TLL (lipase from Thermomyces lanuginosus), AOL (lipase from Aspergillus oryzae), RML (lipase from Rhizomucor miehei), BCL (lipase from Burkholderia cepacia), CALA (Candida antarctica lipase A) and LU (Lecitase® Ultra) were encapsulated into nucleotide‐hybrid metal coordination polymers (CPs). Enzyme concentration was optimized for encapsulation and the enzymatic properties of the obtained lipases were investigated. In addition, their performance in glycerolysis and esterification was evaluated, and glycerolysis conditions (water content, temperature and time) were optimized. RESULTS Hydrolysis activity over 10 000 U g−1 and activity recovery over 90% were observed from AOL@GMP/Tb, TLL@GMP/Tb and RML@GMP/Tb. GMP/Tb encapsulation (of AOL, TLL, RML and LU) improved their thermostability when incubated in air. The encapsulated lipases exhibited moderate [triacylglycerols (TAG) conversion 30–50%] and considerable glycerolysis activity (TAG conversion over 60%). TAG conversions from 69.37% to 82.35% and diacylglycerols (DAG) contents from 58.62% to 64.88% were obtained from CALA@GMP/metal samples (except for CALA@GMP/Cu). Interestingly, none of the encapsulated lipases initiated the esterification reaction. AOL@GMP/Tb, TLL@GMP/Tb, RML@GMP/Tb and CALA@GMP/Tb showed good reusability in glycerolysis, with 88.80%, 94.67%, 89.85% and 78.16% of their initial glycerolysis activity, respectively, remaining after five cycles of reuse. The relationships between temperature and TAG conversion were LnV0 = 6.5364–3.7943/T and LnV0 = 13.8820–6.4684/T for AOL@GMP/Tb and CALA@GMP/Tb, respectively; in addition, their activation energies were 31.55 and 53.78 kJ mol−1, respectively. CONCLUSION Most of the present encapsulated lipases exhibited moderate and considerable glycerolysis activity. In addition, AOL@GMP/Tb, TLL@GMP/Tb, RML@GMP/Tb and CALA@GMP/Tb exhibited good reusability in glycerolysis reactions and potential in practical applications. © 2022 Society of Chemical Industry.

Immobilization of <i>Candida antarctica</i> Lipase A onto Macroporous Resin NKA-9: Esterification and Glycerolysis Performance Study

“…In this study, water was evaporated by a stream of N 2 gas, however the esterification did not proceed, suggesting the present CALA@NKA-9 cannot catalyze the esterification. This was not strange, and similar phenomenon was observed from the coordination polymers encapsulated lipases in our previous study 26) . Interestingly, free CALA was applied to catalyze the esterification of palmitic acid with 2-ethyl-1-hexanol in a water-abundant system, and 2-ethyl-1-hexyl palmitic acid ester was produced at near 100％ yield 71) .…”

“…Herein, temperature at 50℃ was selected for the present glycerolysis. Interestingly, during the CALA@GMP/Tb mediated glycerolysis reaction, temperature at 60℃ was found suitable, and the glycerolysis activity was impaired greatly at 70 and 80℃ 26) .…”

“…Moreover, reusability performance also relates to the stability, including thermostability, solvent stability and sometimes even the pH stability and the storage stability. With better these stabilities, the immobilized enzymes could undoubtedly be used for more cycles 26) . In this study, reusability of CALA@NKA-9 was investigated and results were presented in Fig.…”

“…Therefore, the immobilization of CALA significantly improved its operational stability and in turn the reusability, which was potential in practical application. Interestingly, in the CALA@GMP/Tb mediated glycerolysis reaction, 78.16％ of its initial activity was retained after 5 cycles of reuse 26) .…”

“…In aqueous medium, a large percentage of lipase molecules have their active center covered by a polypeptide chain, which may isolate it from reaction medium. While in the presence of a hydrophobic surface, the lipases becomes adsorbed on it, where the active center is fully exposed, thus being the lipases able to hydrolyze drops of oils 26) .…”