Contents lists available at ScienceDirect Catalysis Today journal homepage: www.elsevier.com/locate/cattod Biocatalytic resolution of (R,S)-styrene oxide using a novel epoxide hydrolase from red mung beans Manoj P. Kamble, Ganapati D. Yadav ⁎ Department of Chemical Engineering, Institute of Chemical Technology, Nathalal Parekh Marg, Matunga, Mumbai, 400019, India ARTICLE INFO Keywords: Biotransformation Epoxides (R,S)-Styrene oxide Red mung beans Epoxy hydrolase Enzyme kinetics ABSTRACT Chiral epoxides are commercially important starting materials for synthesis of active pharmaceutical ingredients and agrochemicals. A major challenge in synthetic chemistry is to produce such compounds in high yield with purity. There have been numerous current advances in the field of biotransformation particularly, hydrolytic kinetic resolution of epoxides using newly discovered enzymes (e.g. epoxide hydrolases). Epoxide hydrolase (EH) is a promising biocatalyst for the synthesis, as it enables racemic preparation of various epoxides and/or their corresponding diols in enantiopure form. In present study, partially purified epoxide hydrolase enzyme isolated from red mung beans was used for the first time for enantioselective hydrolysis of (R,S)-styrene oxide to (R)-1- phenyl-1,2-ethanediol. It was found that the optimal reaction temperature, buffer pH, and substrate con- centration were 40 °C, 7.5 and 20 mM, respectively. Under optimized reaction conditions, conversion, V max and K m values were ∼44%, 8.2 × 10 -3 mol/L/ min and 4.5 mol/L, respectively. 1. Introduction Biotransformation means chemical reactions catalysed by living cells, microorganism or isolated enzymes with superiority over organic synthesis which stem out from high stereo- or regio-selectivity com- bined with high product purity [1–3]. This particular phenomenon can be combined with economic benefit; hence biocatalysis becomes an integral part of innovative organic synthesis [4]. The use of biocatalyst has numerous advantages over traditional chemical catalytic ap- proaches; it shows catalytic activity at ambient conditions (neutral pH, atmospheric pressure, normal temperature) and presents no ecological harm which is one of the mandatory requirements for sustainability [5,6]. Enantiopure epoxides and vicinal diols are commercially valuable chiral building blocks in organic synthesis and can be used as key in- termediates in the production of bioactive compounds such as β- blockers, amino alcohols, anti-obesity drugs, anticancer agents and agrochemicals [5,7–12]. Current approaches for synthesis of selective epoxides and diols include the derivatization of chiral substrates available in nature (chiral pool) and asymmetric synthesis from pro- chiral substrate [8,10]. A major challenge in modern organic chemistry is the synthesis and isolation of such compounds in high conversions with better enantiopurity [1,8]. Epoxides are reactive molecules due to the polarization of the CeO bond and the strain in the three-membered oxirane ring making them so easily accessible for nucleophilic attack [13]. Therefore, various approaches have been tried to synthesize en- antiopure epoxides. An emerging approach is the use of cofactor in- dependent epoxide hydrolase which is an important part of a spectrum of biocatalysts available in synthetic chemistry. Among biocatalytic routes, kinetic resolution of racemic epoxides using epoxide hydrolase is a very promising method in which high enantiopure racemates can be obtained with environmental safety and high economic benefits [7,12,14,15]. The biocatalytic processes typically yield epoxide pro- ducts with excellent enantiomeric excesses (ee). They are particularly valuable for those substrates that are poorly amenable to chemical procedures [5,9]. Epoxide hydrolase (EH, EC 3.3.2.3) is natural-, biodegradable and environment friendly, which has been found in all types of living or- ganisms such as plants, insects, bacteria, yeast, fungi and animals [5,8,9,12,14]. It is a promising biocatalyst for the separation of racemic epoxides and vicinal diols [9]. The cofactor independent EH has several advantages such as high enantio-, regio-, chemo- and stereoselectivity on broad spectrum of substrates, and is highly active in both organic and non-organic reaction media. Therefore it is suitable for operating even at lager scale; it is partially purified and used in powder form without loss of catalytic activity upon storage [8,12,16]. EH can cata- lyse the hydrolysis of epoxide to corresponding diols through addition of water molecules to epoxide rings without any cofactor or metal ions [9]. EH belongs to the α/ß hydrolase fold family and possesses a cat- alytic triad (Asp-His-Asp/Glu) of which the nucleophilic aspartate http://dx.doi.org/10.1016/j.cattod.2017.06.013 Received 15 March 2017; Received in revised form 11 June 2017; Accepted 14 June 2017 ⁎ Corresponding author. E-mail addresses: gd.yadav@ictmumbai.edu.in, gdyadav@yahoo.com (G.D. Yadav). Catalysis Today xxx (xxxx) xxx–xxx 0920-5861/ © 2017 Elsevier B.V. All rights reserved. Please cite this article as: Kamble, M.P., Catalysis Today (2017), http://dx.doi.org/10.1016/j.cattod.2017.06.013