Rhodococcus epoxide hydrolase

In a similar manner, and as shown again by the Faber group, the catalyzed reaction of bis-epoxides led to THFs containing four stereocenters [22]. Thus, treatment of cis,ds,weso-8-51 with the epoxide hydrolase Rhodococcus sp. CBS 71773 predominantly yielded the THF derivative 8-53a in 94% ee and 89% de, whereas the use of other biocatalysts has shown only low to moderate stereoselectivity (Scheme 8.14). As intermediate, the diol 8-52 can be assumed, whereby for the further transformation path A is always favored. 

Van der Werf Ml, KM Overkamp, JAM de Bont (1998) Limonene-1,2-epoxide hydrolase imm Rhodococcus erythropolis DCL14 belongs to a novel class of epoxide hydrolases. J Bacteriol 180 5052-5057. 

By using bacterial epoxide hydrolase of Rhodococcus equi IFO 3730, Faber synthesized44 as shown in Scheme 64 [96]. The enzymatic step (A—>B),however, proceeded in a low yield. 

Optically pure trans- and czs-linalool oxides, constituents of several plants and fruits, are among the main aroma components of oolong and black tea. These compounds were prepared from 2,3-epoxylinalyl acetate (9) (Scheme 17) [102]. The key step consist of a separation of the diastereomeric mixture of 9 by employing an epoxide hydrolase preparation derived from Rhodococcus sp. NCIMB 11216, yielding the product diol and remaining epoxide in excellent diastereomeric excess (de>98%). Further follow-up chemistry gave both linalool... 

Very recently, the purification and characterisation of an epoxide hydrolase, catalysing the conversion of limonene-1,2-epoxide to limonene-1,2-diol has been described [90]. The enzyme was isolated from Rhodococcus erythropolis DCL14 and is induced when the microorganism is grown on monoterpenes. The authors found evidence that the enzyme, limonene-1,2-epoxide hydrolase is the first member of a new class (the third class) of epoxide hydrolases [91]. 

When racemic aryl glycidyl ethers were subjected to aminolysis in aqueous buffer catalyzed by hepatic microsomal epoxide hydrolase from rat, the corresponding (S)-configurated amino-alcohols were obtained in 51-88% ee 131. On the other hand, when azide was employed as nucleophile for the asymmetric opening of 2-methyl-1,2-epoxyheptane in the presence of an immobilized crude enzyme preparation derived from Rhodococcus sp., which contains an epoxide hydrolase activity, the reaction revealed a complex picture 1321. The (S)-epoxide from the racemate was hydrolyzed (as in the absence of azide), and the less readily accepted (i )-enantiomer was transformed into the corresponding azido-alcohol (ee >60%). Although at present only speculations can be made about the actual mechanism of both the aminolysis and azidolysis reaction, in both cases it was proven that the reaction was catalyzed by a protein and that no reaction was observed in the absence of biocatalyst... 

SP 361 SP 409 Immobilized enzyme mixture from Rhodococcus sp. containing nitrilase, nitril hydratase,esterase, epoxide hydrolase and amidase activity discontinued... 

Epoxide Hydrolase Origin Rhodococcus rhodochrous Fluka Lab... 

LEH limonene epoxide hydrolase from Rhodococcus erythropolis DCL14 Leu leucine... 

Barbirato F, Verdoes J, de Bont J, van der Werf M (1998) The Rhodococcus erythropolis DCL14 limonene-l,2-epoxide hydrolase gene encodes an enzyme belonging to a novel class of epoxide hydrolases. FEES Lett 438 293-296... 

Among the sterically more demanding substrates, 2,2-disubstituted oxiranes were hydrolyzed in virtually complete enantioselectivities using enzymes from bacterial sources (E > 200), in particular Mycobacterium NCIMB 10420, Rhodococcus (NCIMB 1216, DSM 43338, IFO 3730) and closely related Nocardia spp. (Scheme 2.93) [608, 609]. All bacterial epoxide hydrolases exhibited a preference for the (S)-enantiomer. In those cases where the regioselectivity was determined, attack was found to exclusively occur at the unsubstituted oxirane carbon atom. 

Epoxide hydrolases have been purified from mammalian liver cells [63-66] but also from microbial sources such as Bacillus megaterium [67], Corynebacterium [45,46,68], Pseudomonas sp. [46,69], and dematiaceous fungi such as Ulocladium atrum and Zopfiella karachiensis [70]. However, some of these enzymes were only partially purified [67,68], or their enantioselectivity was not investigated [69] or was very low [45,46]. More recently, two bacterial epoxide hydrolases with high activity and high enantioselectivity were purified and characterized from Rhodococcus sp. NCIMB 11216 [71] and Nocardia TBl [72]. 

As a consequence of this mechanism, the epoxide is generally opened in a transspecific fashion with one oxygen from water being incorporated into the product diol [69]. For instance, ( )-rranj-epoxysuccinate was converted to me o-tartrate by an epoxide hydrolase isolated from Pseudomonas putida [69]. In a complementary fashion, cij-epoxy-succinate gave d- and L-tartrate (with a Rhodococcus sp.) albeit in low optical purity [93]. In addition, it was shown by OH2 labeling experiments that only one O atom originates from water when both mammalian or bacterial epoxide hydrolases [94] or whole fungal cells [94] were used as catalysts. 

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