CaLB Catalyzed Conversion of ε-Caprolactone in Aqueous Medium. Part 1: Immobilization of CaLB to Microgels

Abstract

Abstract:The enzymatic ring-opening polymerization of lactones is a method of increasing interest for the synthesis of biodegradable and biocompatible polymers. In the past it was shown that immobilization of Candida antarctica lipase B (CaLB) and the reaction medium play an important role in the polymerization ability especially of medium ring size lactones like ε-caprolactone (ε-CL). We investigated a route for the preparation of compartmentalized microgels based on poly(glycidol) in which CaLB was immobilized to increase its esterification ability. To find the ideal environment for CaLB, we investigated the acceptable water concentration and the accessibility for the monomer in model polymerizations in toluene and analyzed the obtained oligomers/polymers by NMR and SEC. We observed a sufficient accessibility for ε-CL to a toluene like hydrophobic phase imitating a hydrophobic microgel. Comparing free CaLB and Novozym ® 435 we found that not the monomer concentration but rather the solubility of the enzyme, as well as the water concentration, strongly influences the equilibrium of esterification and hydrolysis. On the basis of these investigations, microgels of different polarity were prepared and successfully loaded with CaLB by physical entrapment. By comparison of immobilized and free CaLB, we demonstrated an effect of the hydrophobicity of the microenvironment of CaLB on its enzymatic activity.

Microgel organocatalysts: modulation of reaction rates at liquid–liquid interfaces

“…[10][11][12][13][14][15][16][17] Due to their versatile properties, microgels find various applications for drug delivery, as biomaterials or in the field of catalysis. [18][19][20] In last-named applications, microgels enable exploring and controlling chemical reactions in compartments, opening new platforms for bio-inspired catalysts. Here, microgels have been investigated as responsive carrier colloids for catalytically active materials, naming metal nanoparticles, metallic complexes, organocatalysts and enzymes.…”

The effects of macromolecular crowding and surface charge on the properties of an immobilized enzyme: activity, thermal stability, catalytic efficiency and reusability

“…Previous studies have shown that the microenvironment of an immobilized enzyme can determine the performance of the enzyme, with regards to its catalytic activity, stability, and selectivity. [7][8][9] In addition, macromolecular crowding and surface charge are important but neglected aspects of the enzyme microenvironment.…”

Comparison of Candida antarctica Lipase B Variants for Conversion of ε-Caprolactone in Aqueous Medium—Part 2

“…Recently, our groups showed the activity effect of CaLB immobilization to tailored microgels of different polarity [ 30 ]. Providing a more hydrophobic environment in the microgel, the hydrolytic activity was reduced, and the polymerization activity was increased.…”

“…Hereby, the influence of the gel network on the enzymatic activity and the protection against solvents are important research issues among others [ 25 , 26 , 27 ]. Recently, we reported about the synthesis and immobilization of CaLB in tailormade microgels and showed the influence of the microgel polarity on the ring-opening polymerization activity of CaLB [ 28 , 29 , 30 ]. Besides our work Montanier and colleagues published their work on engineering of CaLB for polyester synthesis [ 31 ].…”