title: Nitrite-mediated synthesis of chiral epichlorohydrin using halohydrin dehalogenase from Agrobacterium radiobacter AD1.
abstract: In the current study, the haloalcohol dehalogenase HheC gene from Agrobacterium radiobacter AD1 was synthesized and expressed in Escherichia coli. After purification using Ni-nitrilotriacetic acid affinity chromatography, HheC was used in the synthesis of chiral epichlorohydrin in the presence of NO₂⁻. The optimal pH, temperature, and NO₂⁻ concentration for enantioselectivity are 5.0, 37°C, and 60 mM, respectively. The maximum velocity and Michaelis constant values for (S)-epichlorohydrin are 714.3 µmol min⁻¹ mg⁻¹ and 17.2 mM, respectively, whereas those for (R)-epichlorohydrin are 166.8 µmol min⁻¹ mg⁻¹ and 29.0 mM, respectively. Under optimal conditions, (R)-epichlorohydrin with 99% enantiomeric excess was obtained after an 18 Min reaction; the yield reached 41%, which is the highest amount obtained for chiral epichlorohydrin synthesis using haloalcohol dehalogenase. In addition, (R)-epichlorohydrin with 99% enantiomeric excess was successfully obtained from 1,3-dichloro-2-propanol by the ring opening of racemic epichlorohydrin in the presence of NO₂⁻ after the ring closure of 1,3-dichloro-2-propanol with HheC. To the best of our knowledge, the current study is the first report on the kinetic resolution of epichlorohydrin with NO₂⁻ and synthesis of chiral epichlorohydrin with 99% enantiomeric excess from 1,3-dichloro-2-propanol by combining ring closure of 1,3-dichloro-2-propanol and ring opening of racemic epichlorohydrin.
authors.affiliation: Institute of Bioengineering, Zhejiang University of Technology, Hangzhou, People's Republic of China.
authors.forename: Huo-Xi
authors.initials: HX
authors.lastname: Jin
authors.forename: Zhong-Ce
authors.initials: ZC
authors.lastname: Hu
authors.forename: Zhi-Qiang
authors.initials: ZQ
authors.lastname: Liu
authors.forename: Yu-Guo
authors.initials: YG
authors.lastname: Zheng
mesh_terms: D016960:Agrobacterium tumefaciens / Q000201:enzymology*; D003001:Cloning, Molecular; D004591:Electrophoresis, Polyacrylamide Gel; D004811:Epichlorohydrin / Q000138:chemical synthesis*; D004926:Escherichia coli / Q000235:genetics; D006863:Hydrogen-Ion Concentration; D006867:Hydrolases / Q000378:metabolism*; D007218:Industrial Microbiology / Q000379:methods*; D015394:Molecular Structure; D009573:Nitrites / Q000378:metabolism*; D013237:Stereoisomerism; D013696:Temperature
chemical_list: D009573:Nitrites; D004811:Epichlorohydrin; D006867:Hydrolases; C430848:halohydrin dehalogenase