At the moment, there are approx. 100 published papers investigating halohydrin dehalogenases from different aspects; enzymology, molecular biology and reactions they can catalyse. Unquestionably, these enzymes are of great importance and hold an immense potential due to the wide spectrum of different compounds that can be synthesized by their action. These compounds, such as chiral epoxides, β‐substituted alcohols, oxazolidinones etc., significantly enrich the chemist's toolbox and, moreover, open the possibility for the synthesis of even more complex compounds. Still, there are many unknowns, and it is the purpose of this work to demonstrate the possibilities and bottlenecks, in scientific sense, that could further help in broadening the applicative potential of these fascinating enzymes.

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Optically pure fluorinated organic azides represent synthetically valuable building blocks in a range of industrial applications. Since direct fluorination of molecules is challenging from both economic and environmental perspective, the...

What is the most significant result of this study?Our research addresses a fast-developing area of biocatalysis, focusing on the interactions between the enzyme halohydrin dehalogenase and solvent molecules. The ability of enzymes to operate in organic solvents is the basis of extensive research in enzymology. We have performed the first comprehensive study of the mechanisms by which DMSO, the most commonly used co-solvent in the halohydrin dehalogenase-catalyzed reactions, influences the activity and stability of the enzyme HheC. The contribution of this work is manifold. It involved experimental kinetic studies and investigation of the structural changes that occur under operational conditions. MD simulations of this tetrameric enzyme in aqueousorganic media, applied for the first time in the study of halohydrin dehalogenases, in general, provide unique information about interactions at the molecular level.

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Although the application of organic solvents in biocatalysis is well explored, in-depth understanding of the interactions of solvent with proteins, in particular oligomeric ones, is still scant. Understanding these interactions is essential in tailoring enzymes for industrially relevant catalysis in nonaqueous media. In our study, the homotetrameric enzyme halohydrin dehalogenase (HHDH) from Agrobacterium radiobacter AD1 (HheC) was investigated, as a model system, in DMSO/water solvent mixtures. DMSO, the most commonly used co-solvent for biocatalytic transformations, was found to act as a mixed-type inhibitor with a prevalent competitive contribution. Even 5 % (v/v) DMSO inhibits the activity of HheC by half. Molecular dynamics (MD) simulations showed that DMSO keeps close to Ser-Tyr catalytic residues forming alternate H-bonds with them. Stability measurements paired with differential scanning calorimetry, dynamic light scattering methods and MD studies revealed that HheC maintains its structural integrity with as much as 30 % (v/v) DMSO.

Remedijacija tala onečišćenih kompleksnim mješavinama organskih tvari i teških metala jedan je od najvećih izazova obnavljanja okoliša. Fitoremedijacija je naziv za skup postupaka koji upotrebljavaju biljke, njihove enzime i prisutne mikroorganizme iz zone korijenja za izolaciju, transport, detoksikaciju i mineralizaciju ksenobiotika, čime se smanjuje njihova koncentracija, pokretljivost ili toksični učinci. Fitoekstrakcija, fitostabilizacija, fitovolatizacija, fitorazgradnja i rizorazgradnja imaju velik potencijal za nedestruktivnu remedijaciju tala, što pokazuju brojna istraživanja u laboratorijskom mjerilu. Kako bi fitoremedijacija postala pouzdana tehnologija za širok spektar primjena u većem mjerilu, potrebno je ulagati resurse u nova istraživanja s ciljem boljeg razumijevanja procesa u cjelini, posebice na genetičkoj i biokemijskoj razini.