New applications of biocatalysts.

Over the past year, new applications for biocatalysts have continued to be developed. This has been made possible by the study of new enzymes, the genetic and chemical modification of old enzymes, and the utilization of unique reaction conditions that alter enzyme properties and improve catalytic performance.

New applications of biocatalysts.

The development of new biocatalytic applications continues to advance in several directions. Over the past year, new enzymes have been discovered and their potential in biocatalyst applications has been researched. In addition, new chemical and genetic modifications have been made in the development of novel fermentation processes.

Isolation and characterization of a novel nonheme chloroperoxidase.

Chloroperoxidase, purified from the fermentation of Curvularia inaequalis, had a molecular weight of approximately 240,000 and was composed of 4 subunits of identical molecular weight (Mr 66,000). The enzyme was specific for I-, Br- and Cl-, and inactive toward F-. The optimum pH of the enzyme was centered around 5.

Epoxidation of alkenes by chloroperoxidase catalysis.

Chloroperoxidase from Caldariomyces fumago catalyzes the peroxidation of alkenes to epoxides. This enzyme is the only haloperoxidase of four tested capable of carrying out the reaction. These results further establish chloroperoxidase as a unique haloperoxidase, and adds this enzyme to the short list of other enzymes (e.

DMSO is a substrate for chloroperoxidase.

Dimethyl sulfoxide has been used as a nonaqueous organic solvent in haloperoxidase reactions. However, it has been found that this solvent is not inert under chloroperoxidase reaction conditions, forming the halosulfoxide, the sulfone, and the halosulfone. The biological significance of this finding is briefly discussed.

Peroxide oxidation of primary alcohols to aldehydes by chloroperoxidase catalysis.

Chloroperoxidase catalyzes the peroxidation of primary alcohols, specifically those that are allylic, propargylic, or benzylic. Aldehydes are the products. The reaction displays appreciable activity throughout the entire pH range investigated, namely pH 3.

Novel haloperoxidase reaction: synthesis of dihalogenated products.

The enzymatic synthesis of vicinal, dihalogenated products from alkenes and alkynes is described. The enzymatic reaction required an alkene or alkyne, dilute hydrogen peroxide, a haloperoxidase, and molar amounts of halide ions. Vicinal dichloro, dibromo, and diiodo products could be formed.

Production of Epoxides from alpha,beta-Halohydrins by Flavobacterium sp.

The relative activity of Flavobacterium whole cells on the enzymatic synthesis of epoxides from alpha,beta-chlorohydrins, -bromohydrins, and -iodohydrins is described.

Novel haloperoxidase substrates. Alkynes and cyclopropanes.

Two new substrate classes that can be halogenated by haloperoxidase have been discovered. The enzymatic halogenation of alkynes yields alpha-halogenated ketones, and the enzymatic halogenation of cyclopropanes yields alpha, gamma-halohydrins. The general reaction scheme proposed involves the initial formation of hypohalous acid as the key intermediate.

Haloperoxidases: Enzymatic Synthesis of alpha,beta-Halohydrins from Gaseous Alkenes.

The enzymatic synthesis of alpha,beta-halohydrins from gaseous alkenes is described. The enzymatic reaction required an alkene, a halide ion, dilute hydrogen peroxide, and a haloperoxidase enzyme. A wide range of gaseous alkenes were suitable for this reaction, including those containing isolated, conjugated, and cumulative carbon-carbon double bonds.