Sporopollenin as an efficient green support for covalent immobilization of a lipase

Sporopollenin exine capsules (SECs), derived from the spores of Lycopodium clavatum, have been functionalised with 1,n-diamines and the resulting aminoalkyl microcapsules used to immobilize Candida antarctica lipase B (Cal B) via a glutaradehyde-based diimine covalent linker. The supported enzyme efficiently catalyzes the esterification of oleic acid with ethanol. Initial rates using the SEC-CalBs were comparable to the commercial enzyme Novozym 435, but displayed up to 20-fold higher specific activity. The supported enzymes could also be recycled and after four cycles displayed only a modest decrease in conversions. In a kinetic resolution the SEC-CalBs efficiently acetylated rac-1-phenylethanol, with conversions up to 37% after 5 hours and product enantiomeric excesses of >99%. Related to this, the dynamic resolution of rac-1-phenylethylamine, in the presence of Pd-BaSO₄ and ammonium formate, led to the acetylated amine with a 94% conversion and >99% ee

Novel nanoparticle/enzyme biosilicified nanohybrids for advanced heterogeneously catalyzed protocols

Novel bio-nanohybrids based on room temperature one-pot synthesized lipase-nanoparticle systems were developed and characterized in this work, with subsequent investigations of their catalytic activities and stability as compared to the free enzymes. Preliminary results revealed excellent stabilities, solvent tolerance, and activities as compared to free lipases, opening up further scenarios for their utilization under continuous flow conditions as well as in tandem reactions

Nanoencapsulated Lecitase Ultra and <i>Thermomyces lanuginosus</i> Lipase, a Comparative Structural Study

Two commercially available and widely used enzymes, the parent <i>Thermomyces lanuginosus</i> lipase (TLL) and the shuffled phospholipase A1 Lecitase (Lecitase Ultra), were encapsulated in AOT/isooctane reverse micelles and evaluated regarding their structure and activity. Preparations were also tested as effective biocatalysts. Small-angle X-ray scattering (SAXS), electronic paramagnetic resonance (EPR), and fluorescence spectroscopy were the techniques applied to assess the effects of enzyme incorporation to a reverse micellar nanostructure. SAXS analysis showed that the radius of gyration (<i>R</i>_g) changed from 16 to 38 Å, as the water content (<i>w</i>₀) increased. Elongated shapes were more commonly observed than spherical shapes after enzyme encapsulation. EPR studies indicated that enzymes do not participate in the interface, being located in the aqueous center. Fluorescence energy transfer showed that TLL is located in the water core, whereas Lecitase Ultra is closer to the interface. Enzymatic activity toward a standard esterification reaction endured after the enzyme was incorporated into the micelles. The activity of TLL for systems with <i>w</i>₀ 15 showed the highest conversion yield, 38% in 2 h, while the system with <i>w</i>₀ 10 showed the highest initial velocity, 0.43 μM/min. This last system had a <i>R</i>_g of 19.3 Å, similar to that of the TLL monomer. Lecitase Ultra showed the highest conversion yields in systems with <i>w</i>₀ 10, 55% in 2 h. However, the initial rate was much lower than that of TLL, suggesting less affinity for the substrates, which is expected since Lecitase Ultra is a phospholipase. In summary, we here used several spectroscopic and scattering techniques to reveal the shape and stability of TTL and Lecitase Ultra encapsulated systems, which allowed the selection of <i>w</i>₀ values to provide optimized enzymatic activity