Enzyme chloroperoxidase

In this work, we have grafted the mesoporous SBA-15 materials with 3-aminopropyl trimethoxysilane [10], In a subsequent step, the aminopropyl moiety was reacted with glutardialdehyde, which reacts also with amino groups of the enzymes chloroperoxidase (CPO) and glucose oxidase (GOx) (Scheme 1). 

The heme enzyme chloroperoxidase (CPO), produced by the marine fungus Caldariomycesfumago, is a versatile enzyme which exhibits a broad spectrum of chemical reactivities and it is recognized as a most promising biocatalyst for synthetic applications. Recently, pure (R)-phenyl methylsulfoxide (ee > 99 %) was prepared by chemo- and stereo-selective oxidation of phenyl methylsulfide with CPO in citrate buffer-ionic liquid mixtures. ... 

As already reported in Section II.A.2, the enzymes chloroperoxidase (CPO) and Copri-nus peroxidase (CiP) catalyze the enantioselective oxidation of aryl alkyl sulfides. If a racemic mixture of a chiral secondary hydroperoxide is used as oxidant, kinetic resolution takes place and enantiomerically enriched hydroperoxides and the corresponding alcohols can be obtained together with the enantiomerically enriched sulfoxides. An overview of the results obtained in this reaction published by Wong and coworkers, Hoft and... 

Messerschmidt A, Wever R (1996) X-ray Structure of a Vanadium-Containing Enzyme Chloroperoxidase from the Fungus Curvularia inaequalis. Proc Natl Acad Sci USA 93 392... 

A. Messerschmidt and R. Wever, X-ray structure of a vanadium-containing enzyme chloroperoxidase from the fungus Curvularia inaequalis, Proc. Natl. Acad. Sci. USA 1996, 93, 392-96. 

Messerschmidt, A., Prade, L. and Wever, R. (1997) Implications for the catalytic mechanism of the vanadium-containing enzyme chloroperoxidase from the fungus Curvularia inaequalis by X-ray structures of the native and peroxide form. Biol. Chem., 378, 309. 

Another notoriously ill-behaved group of substrates are the terminal alkenes, which lack the steric definition necessary for most catalytic systems. As an alternative methodology, the enzyme chloroperoxidase has been examined for the epoxidation of 2-methyl-1-alkenes (e.g., 17). Yields tend to be low ee s, although variable, can be quite high [95JA6412]... 

Finally, but certainly not least, we note that the enzyme chloroperoxidase (CPO), catalyzes the highly enantioselective (>98% ee) sulfoxidation of a range of substituted thioanisoles [308]. In contrast to the epoxidation of alkenes, where turnover frequencies were low (see above), in the case of sulfoxidation of thioa-nisole a turnover frequency of around 16 s-1 and a total turnover number of 125000 could be observed. A selection of data is represented in Fig. 4.112. Besides aryl alkyl sulfides, also dialkylsulfides could be oxidized with reasonable enantioselectivities [27]. 

Epoxides are key chiral synthetic intermediates and their enantioselective preparation by oxidation of achiral alkenes is a key reaction in many synthetic strategies. Sharpless asymmetric epoxidation is suitable for most allylic alcohols [26, 27], but few general procedures exist for unfunctionalized olefins. Jacobsen s manganese salen-mediated epoxidation is suitable for and gives good selectivities with Z-olefins (85 to 90% ee) [28]. The enzyme chloroperoxidase... 

Cpd I irrespective of whether the proximal ligand was HS, CHjS or a more extensive chunk of the cysteine loop. Thus, in accord with experimental results on the analogous Cpd I species of the enzyme chloroperoxidase, Cpd I of P450cam is a doublet state and it corresponds to the green species. ... 

These studies support the proposal that the enzyme chloroperoxidase initiates the biosynthesis by chlorinating the -indole or C-4 carbon of tryptophan, followed by formation of a new pyrrole ring and loss of the chlorine atom (Scheme 11). This route (pathway a) includes the penultimate step of chlorination of both aromatic rings before the oxidative conversion of the aromatic amino-group into a nitro-group. This biosynthetic proposal requires electrophilic chlorination of the 3-position of the pyrrole ring, which normally reacts with electrophiles at C-2 or C-5. 

Figure 6. Oxidation of arylamine compounds by the fimgal enzyme chloroperoxidase to form nitrosoarene products.

The isolated enzyme chloroperoxidase from Caldariomyces fumago is reported to perform stereoselective epoxidation reactions and in one example, oxidation of a-meth-... 

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