Delayed In Vivo Encapsulation of Enzymes Alters the Catalytic Activity of Virus-Like Particle Nanoreactors

Encapsulation of enzymes inside protein cage structures, mimicking protein-based organelle structures found in nature, has great potential for the development of new catalytic materials with enhanced properties. In vitro and in vivo methodologies have been developed for the encapsulation of enzymes within protein cage structures of several types, particularly virus-like particles (VLPs), with the ability to retain the activity of the encapsulated enzymes. Here, we examine the in vivo encapsulation of enzymes within the bacteriophage P22 derived VLP and show that some enzymes may require a delay in encapsulation to allow proper folding and maturation before they can be encapsulated inside P22 as fully active enzymes. Using a sequential expression strategy, where enzyme cargoes are first expressed, allowed to fold, and later encapsulated by the expression of the P22 coat protein, altered enzymatic activities are obtained in comparison to enzymes encapsulated in P22 VLPs using a simultaneous coexpression strategy. The strategy and results discussed here highlight important considerations for researchers investigating the encapsulation of enzymes inside confined reaction environments via in vivo routes and provide a potential solution for those that have been unable to produce active enzymes upon encapsulation.

Visible-Light-Induced Decarboxylative Alkylation/Ring Opening and Esterification of Vinylcyclopropanes

A visible-light-induced four-component reaction of vinylcyclopropanes, N-(acyloxy)phthalimide esters, N,N-dimethylformamide (DMF), and H₂O through an oxidative ring opening of cyclopropane is presented. This procedure provides a new and effective way to construct formate esters. DMF is employed as both a solvent and the source of CHO. This difunctionalization of vinylcyclopropanes shows good functional group tolerance under room temperature. A radical pathway is involved, and carbonyl oxygen of ester originated from water in this transformation.

One-Pot Conversion of Cinnamaldehyde to 2-Phenylethanol via a Biosynthetic Cascade Reaction

A novel biosynthetic pathway for the production of natural 2-phenylethanol from cinnamaldehyde is reported. An ene-reductase (OYE)-mediated selective hydrogenation of cinnamaldehyde to hydrocinnamaldehyde is followed by a regioselective Baeyer-Villiger oxidation (BVMO) to produce the corresponding formate ester that either spontaneously hydrolyzes to 2-phenylethanol in water or is assisted by a formate dehydrogenase (FDH). This cascade reaction is performed in a one-pot fashion at ambient temperature and pressure. High selectivity and complete conversion were achieved.

Hybrid molecular/enzymatic catalytic cascade for complete electro-oxidation of glycerol using a promiscuous NAD-dependent formate dehydrogenase from Candida boidinii

The formate dehydrogenase from Candida boidinii was combined with NH₂-TEMPO to form a novel hybrid anode to oxidize glycerol to carbon dioxide at near-neutral pH.

Efficient production of (R)-2-hydroxy-4-phenylbutyric acid by using a coupled reconstructed D-lactate dehydrogenase and formate dehydrogenase system

Background

(R)-2-Hydroxy-4-phenylbutyric acid [(R)-HPBA] is a key precursor for the production of angiotensin-converting enzyme inhibitors. However, the product yield and concentration of reported (R)-HPBA synthetic processes remain unsatisfactory.

Methodology/Principal Findings

The Y52L/F299Y mutant of NAD-dependent d-lactate dehydrogenase (d-nLDH) in Lactobacillus bulgaricus ATCC 11842 was found to have high bio-reduction activity toward 2-oxo-4-phenylbutyric acid (OPBA). The mutant d-nLDH^Y52L/F299Y was then coexpressed with formate dehydrogenase in Escherichia coli BL21 (DE3) to construct a novel biocatalyst E. coli DF. Thus, a novel bio-reduction process utilizing whole cells of E. coli DF as the biocatalyst and formate as the co-substrate for cofactor regeneration was developed for the production of (R)-HPBA from OPBA. The biocatalysis conditions were then optimized.

Conclusions/Significance

Under the optimum conditions, 73.4 mM OPBA was reduced to 71.8 mM (R)-HPBA in 90 min. Given its high product enantiomeric excess (>99%) and productivity (47.9 mM h⁻¹), the constructed coupling biocatalysis system is a promising alternative for (R)-HPBA production.