Saul L. Neidleman

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 3.0-7.0. This enzyme is the only haloperoxidase of four tested capable of carrying out the reaction. These results further establish chloroperoxidase as a unique haloperoxidase.

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.g., cytochrome P-450) known to epoxidize alkenes.

Saturated and Unsaturated Wax Esters Produced by Acinetobacter sp. HO1-N Grown on C16-C20 n-Alkanes

The wax ester compositions produced by the action of Acinetobacter sp. HO1-N on n-alkanes (C16 through C20) were analyzed using capillary gas chromatography/mass spectrometry (GC/MS). The wax esters contained, surprisingly, a large percentage of mono-and diunsaturated components. The acyl and alkoxy segments are reported for each wax ester component. Also, the positions of the carbon-carbon double bonds in the wax esters produced from the C16 and C20 n-alkanes are reported. These microbial-produced wax ester mixtures bear a close chemical similarity to those of sperm whale and jojoba oils.

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 5.0. X-ray fluorescence revealed that the enzyme contained 2.2 atoms of zinc and 0.7 atom of Fe per molecule of protein. The enzyme had no heme-like compound as a prosthetic group, making it the first nonheme chloroperoxidase to be reported. Under oxidative conditions that rapidly inactivated other haloperoxidases, this enzyme was remarkably stable.

Convenient, laboratory procedure for producing solid d-arabino-hexos-2-ulose (d-glucosone)

Abstract The production of solid d - arabino -hexos-2-ulose ( d -glucosone) from d -glucose by use of an enzyme, pyranose-2-oxidase (EC 1.1.3.10), is described. The enzyme is extracted from the mycelia of Polyporus obtusus , partially purified, and then immobilized on activated CH-Sepharose 4B. The enzymic conversion of d -glucose into d -glucosone is simple and convenient, and provides a product free from residual d -glucose. Lyophilization of the filtered reaction-solution yields the product, solid d -glucosone. Assay methods have been developed for monitoring the enzymic reaction and evaluating the purity of the final product.

Biotechnology and oleochemicals: Changing patterns

Biotechnology will have a broad impact on the oleochemicals industry. Only a narrow range of this interface is discussed: (a) the use of organic solvents in the enzymatic synthesis of lipid derivatives, (b) the effect of the chemical nature of the feedstock on the production of microbial monoesters, and (c) temperature as a determinant of the level of unsaturation in biosynthetic lipids. Interest in running enzymatic reactions in high concentrations of organic solvents is increasing. The implications of such processes for the oleochemical industry is illustrated by examples of ester synthesis and interesterification of oils and fats. The dramatic effect of feedstock chemistry on the final monoester product mix produced byAcinetobacter sp. HO1-N is also discussed. Products resulting from usingn-alkanes (C16−C20), acetic and propionic acids and, most recently, ethanol and propanol, are illustrated. They range from a monoester mix resembling sperm oil to one similar to jojoba oil. In general, temperature inversely affects biolipid unsaturation: the low the temperature, the greater the unsaturation. The major function of this response is to preserve fluidity and function in biological membranes. The effect is universal in nature, occurring in animals, plants and microorganisms. Controlled laboratory studies have supported these observations made in nature. We have investigated the effect of temperature on the unsaturation of monoesters produced by the bacterium,Acimetobacter sp. HO1-N. The inverse relationship between temperature and unsaturation is clearly shown. The enzymatic basis for these results and the possibility of chemical or genetic modification of plants and microorganisms to produce more or less unsaturated lipids is briefly discussed. Organic solvents, feedstock chemistry and temperature stress in biocatalysis are but three of the variables at the interface of biotechnology and the oleochemicals industry that will cause changing patterns.

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.

Biological halogenation: roles in nature, potential in industry.

Abstract Haloperoxidases are enzymes that catalyze halogenation in nature. Their functions and those of their reaction products are obscure in many cases. This review considers some of what is known and speculates on some of what is unknown, including the potential of these enzymes for commercial exploitation.

The enzymatic synthesis of heterogeneous dihalide derivatives: a unique biocatalytic discovery

Abstract Using purified enzymes, the first transformations of unhalogenated organic substrates to heterogeneous dihalogenated products are reported, including the first enzyme-associated synthesis of a carbon—fluorine bond.

Halonium ion-induced biosynthesis of chlorinated marine metabolites

Abstract Bromoperoxidases do not directly oxidize the chloride ion; nevertheless, in the presence of bromide ions, chloride ions and hydrogen peroxide, bromoperoxidases react with alkenes and alkynes to produce bromochloroderivatives. This same reaction is catalysed when seawater is the source of chloride and bromide ions. This suggests that bromonium ion-induced biosynthesis of chlorinated metabolites occurs in marine environments. The role of iodonium ions in the biosynthesis of chlorinated metabolites is also discussed.