title: Limonene-1,2-epoxide hydrolase from Rhodococcus erythropolis DCL14 belongs to a novel class of epoxide hydrolases.
abstract: An epoxide hydrolase from Rhodococcus erythropolis DCL14 catalyzes the hydrolysis of limonene-1,2-epoxide to limonene-1,2-diol. The enzyme is induced when R. erythropolis is grown on monoterpenes, reflecting its role in the limonene degradation pathway of this microorganism. Limonene-1,2-epoxide hydrolase was purified to homogeneity. It is a monomeric cytoplasmic enzyme of 17 kDa, and its N-terminal amino acid sequence was determined. No cofactor was required for activity of this colorless enzyme. Maximal enzyme activity was measured at pH 7 and 50 degrees C. None of the tested inhibitors or metal ions inhibited limonene-1,2-epoxide hydrolase activity. Limonene-1,2-epoxide hydrolase has a narrow substrate range. Of the compounds tested, only limonene-1,2-epoxide, 1-methylcyclohexene oxide, cyclohexene oxide, and indene oxide were substrates. This report shows that limonene-1,2-epoxide hydrolase belongs to a new class of epoxide hydrolases based on (i) its low molecular mass, (ii) the absence of any significant homology between the partial amino acid sequence of limonene-1,2-epoxide hydrolase and amino acid sequences of known epoxide hydrolases, (iii) its pH profile, and (iv) the inability of 2-bromo-4'-nitroacetophenone, diethylpyrocarbonate, 4-fluorochalcone oxide, and 1, 10-phenanthroline to inhibit limonene-1,2-epoxide hydrolase activity.
authors.affiliation: Division of Industrial Microbiology, Department of Food Technology and Nutritional Sciences, Wageningen Agricultural University, 6700 EV Wageningen, The Netherlands mariet.vanderWerf@imb.ftns.wau.nl
authors.forename: M J
authors.initials: MJ
authors.lastname: van der Werf
authors.forename: K M
authors.initials: KM
authors.lastname: Overkamp
authors.forename: J A
authors.initials: JA
authors.lastname: de Bont
mesh_terms: D000595:Amino Acid Sequence; D000081005:Cyclohexane Monoterpenes; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004851:Epoxide Hydrolases / Q000737:chemistry / Q000145:classification / Q000302:isolation & purification*; D006863:Hydrogen-Ion Concentration; D008670:Metals / Q000494:pharmacology; D008969:Molecular Sequence Data; D008970:Molecular Weight; D039821:Monoterpenes; D010087:Oxides / Q000378:metabolism; D012240:Rhodococcus / Q000201:enzymology*; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity; D013696:Temperature; D013729:Terpenes / Q000378:metabolism*
chemical_list: D000081005:Cyclohexane Monoterpenes; D004791:Enzyme Inhibitors; D008670:Metals; D039821:Monoterpenes; D010087:Oxides; D013729:Terpenes; C028940:limonene-1,2-epoxide; D004851:Epoxide Hydrolases