Abstract
Lipase B from Candida antarctica (CAL-B) is largely employed as a biocatalyst for hydrolysis, esterification, and transesterification reactions. CAL-B is a good model enzyme to study factors affecting the enzymatic structure, activity and/or stability after an immobilization process. In this study, we analyzed the immobilization of CAL-B enzyme on different magnetic nanoparticles, synthesized by the coprecipitation method inside inverse micelles made of zwitterionic surfactants, with distinct carbon chain length: 4 (ImS4), 10 (ImS10) and 18 (ImS18) carbons. Magnetic nanoparticles ImS4 and ImS10 were shown to cross-link to CAL-B enzyme via a Michael-type addition, whereas particles with ImS18 were bond via pyridine formation after glutaraldehyde cross-coupling. Interestingly, the Michael-type cross-linking generated less stable immobilized CAL-B, revealing the influence of a cross-linking mode on the resulting biocatalyst behavior. Curiously, a direct correlation between nanoparticle agglomerate sizes and CAL-B enzyme reuse stability was observed. Moreover, free CAL-B enzyme was not able to catalyze transesterification due to the high methanol concentration; however, the immobilized CAL-B enzyme reached yields from 79.7 to 90% at the same conditions. In addition, the transesterification of lipids isolated from oleaginous yeasts achieved 89% yield, which confirmed the potential of immobilized CAL-B enzyme in microbial production of biodiesel.
Highlights
Enzyme immobilization is largely known as an empiric technique to obtain more stable and active enzymes [1]
Lipase B from Candida antarctica was used as a model enzyme to study the effects of immobilization on the structure, activity, and stability
Three different magnetic nanoparticles were synthesized by the coprecipitation method using zwitterionic surfactants
Summary
Enzyme immobilization is largely known as an empiric technique to obtain more stable and active enzymes [1]. Despite of the studies describing enzyme immobilization on magnetic nanoparticles, little is known on how the enzyme structure is affected when it is immobilized on different support types and sizes, and even on how the cross-linking agents affect the binding between enzyme and support [10], modifying the enzymatic catalysis. The CAL-B enzyme has the advantage of being able to perform a wide variety of reactions, such as hydrolysis, transesterification, and aldol reactions This enzyme has been used for biofuel synthesis, but since CAL-B has the drawback of being inactivated by methanol due to the replacement of water molecules to alcohol in the protein surface [11], immobilization protocols were developed to improve its stability in presence of methanol [12,13]. We attempt to analyze the influence of different reverse micelle–made magnetic nanoparticles and glutaraldehyde cross-linking on the activity and stability of CAL-B for oil transesterification reaction in methanol (Scheme 1).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
