Chemoenzymatic halogenation of phenols by using the haloperoxidase from Curvularia inaequalis

The vanadium-​dependent chloroperoxidase from Curvularia inaequalis is an efficient biocatalyst for the in situ generation of hypohalous acids and subsequent electrophilic oxidn.​/halogenation reactions. Esp., its superb activity and stability under operational conditions make it an attractive catalyst for org. synthesis. Herein, the efficient bromination of thymol was investigated, and turnover nos. of the enzyme were found to exceed 2 000 000. The major novelty of the work is that vanadium chloroperoxidase is more useful as a brominating enzyme than vanadium bromoperoxidase in terms of operational stability, besides being far more stable than heme-​contg. peroxidases

Thymol Bromination - A Comparison between Enzymatic and Chemical Catalysis

The catalytic activity of the vanadium-dependent bromoperoxidase isolated from the brown alga Ascophyllum nodosum is compared with the activity of a cheap, commercially available V-catalyst precursor in the bromination of thymol. Organic solvents have been avoided to make the system appealing from a sustainable chemistry point of view. It is noteworthy that, notwithstanding the low solubility of the substrate, the thymol bromination reactions were performed in water, with a safe brominating source, under mild conditions, and with relatively inexpensive reagents. In this regard, the greenness of the systems was evaluated by the estimation of the E-factor value; the result is that the chemical reaction has a lower environmental impact than the enzymatic process, with an E-factor in the range of eco-friendly processes

Halofunctionalization of alkenes by vanadium chloroperoxidase from Curvularia inaequalis

The vanadium-dependent chloroperoxidase from Curvularia inaequalis is a stable and efficient biocatalyst for the hydroxyhalogenation of a broad range of alkenes into halohydrins. Up to 1 200 000 TON with 69 s−1 TOF were observed for the biocatalyst. A bienzymatic cascade to yield epoxides as reaction products is presented

Marine Vanadium-Dependent Haloperoxidases, Their Isolation, Characterization, and Application

Vanadium-dependent haloperoxidases in seaweeds, cyanobacteria, fungi, and possibly phytoplankton play an important role in the release of halogenated volatile compounds in the environment. These halocarbons have effects on atmospheric chemistry since they cause ozone depletion. In this chapter, a survey is given of the different sources of these enzymes, some of their properties, the various methods to isolate them, and the bottlenecks in purification. The assays to detect and quantify haloperoxidase activity are described as well as their kinetic properties. Several practical tips and pitfalls are given which have not yet been published explicitly. Recent developments in research on structure and function of these enzymes are reviewed. Finally, the application of vanadium-dependent haloperoxidases in the biosynthesis of brominated and other compounds is discussed