Sulfoxidation Of Thioanisole Research Articles

Dual‐Functional Small Molecules for Generating an Efficient Cytochrome P450BM3 Peroxygenase

AbstractWe report a unique strategy for the development of a H2O2‐dependent cytochrome P450BM3 system, which catalyzes the monooxygenation of non‐native substrates with the assistance of dual‐functional small molecules (DFSMs), such as N‐(ω‐imidazolyl fatty acyl)‐l‐amino acids. The acyl amino acid group of DFSM is responsible for bounding to enzyme as an anchoring group, while the imidazolyl group plays the role of general acid–base catalyst in the activation of H2O2. This system affords the best peroxygenase activity for the epoxidation of styrene, sulfoxidation of thioanisole, and hydroxylation of ethylbenzene among those P450–H2O2 system previously reported. This work provides the first example of the activation of the normally H2O2‐inert P450s through the introduction of an exogenous small molecule. This approach improves the potential use of P450s in organic synthesis as it avoids the expensive consumption of the reduced nicotinamide cofactor NAD(P)H and its dependent electron transport system. This introduces a promising approach for exploiting enzyme activity and function based on direct chemical intervention in the catalytic process.

Bifunctional Porphyrin-Based Nano-Metal-Organic Frameworks: Catalytic and Chemosensing Studies.

The use of 5,10,15,20-tetrakis( p-phenylphosphonic acid)porphyrin (H10TPPA) as a linker in the preparation of porphyrin-based metal-organic frameworks (Por-MOFs) through coordination to lanthanides cations is reported. The resulting unprecedented materials, formulated as [M(H9TPPA)(H2O) x]Cl2· yH2O [ x + y = 7; M3+ = La3+ (1), Yb3+ (2), and Y3+ (3)], prepared using hydrothermal synthesis, were extensively characterized in the solid-state, for both their structure and thermal robustness, using a myriad of solid-state advanced techniques. Materials were evaluated as heterogeneous catalysts in the oxidation of thioanisole by H2O2 and as chemosensors for detection of nitroaromatic compounds (NACs). Nano-Por-MOFs 1-3 proved to be effective as heterogeneous catalysts in the sulfoxidation of thioanisole, with Por-MOF 1 exhibiting the best catalytic performance with a conversion of thioanisole of 89% in the first cycle and with a high selectivity for the sulfoxide derivative (90%). The catalyst maintained its activity roughly constant in three consecutive runs. Por-MOFs 1-3 can be employed as chemosensors because of a measured fluorescence quenching up to 70% for nitrobenzene, 1,4-dinitrobenzene, 4-nitrophenol, and phenol, with 2,4,6-trinitrophenol exhibiting a peculiar fluorescence profile.

Improved rate of substrate oxidation catalyzed by genetically-engineered myoglobin

This study showcases the potential of unnatural amino acids to enable non-natural functions when incorporated in the protein scaffold of heme metalloproteins. For this purpose, a genetically-engineered myoglobin (Mb) mutant was created by incorporating redox-active 3-amino-l-tyrosine (NH2Tyr) into its active site, replacing the distal histidine (H64) with NH2Tyr. In peroxide-shunt assays, this variant exhibits an increased rate of turnover for thioanisole and benzaldehyde oxidation as compared to the wild-type (WT) Mb. Indeed, in the presence of excess hydrogen peroxide (H2O2), a 9-fold and 81-fold increase in activity was observed over multiple turnovers for thioanisole sulfoxidation and benzoic acid formation, respectively. The increased oxidation activity in the H64NH2Tyr Mb mutant underlined the role of NH2Tyr in the distal active-site scaffold in peroxide activation. Kinetic, electrochemical, and EPR spectroscopic experiments were performed. On the basis of these studies, it is argued that the single NH2Tyr residue within the Mb variant simultaneously serves the role of the conserved His/Arg-pair within the distal pocket of horseradish peroxidase.

Substitution of an amino acid residue axially coordinating to the heme molecule in hexameric tyrosine-coordinated hemoprotein to enhance peroxidase activity

To convert an originally tyrosine-coordinated heme to histidine-coordinated heme in hexameric tyrosine-coordinated hemoprotein, HTHP, Tyr45, a residue coordinating to the heme cofactor, and Arg25 located in the distal site are replaced with Phe45 and His25, respectively in each of the subunits of the protein. The obtained HTHP mutant (HTHP[Formula: see text] was characterized by SDS-PAGE, ESI-TOF MS, dynamic light scattering measurements and size exclusion chromatography. These analyses indicate that HTHP[Formula: see text] maintains its stable hexameric structure with the altered ligation of each of the heme cofactors. Comparison of UV-vis absorption spectra of the ferric-, ferrous-, CO- and CN-forms of HTHP[Formula: see text] with those of several well-known His-ligated hemoproteins indicates that heme is coordinated by the His25 residue. The reaction of HTHP[Formula: see text] with cumene hydroperoxide produces both cumyl alcohol and acetophenone in a 2.3:1 ratio, indicating that heterolytic O–O bond cleavage dominantly occurs to form the two-electron oxidized species known as compound I. Peroxidase activity of HTHP[Formula: see text] is found to follow Michaelis–Menten kinetics. The [Formula: see text] values of HTHP[Formula: see text] for H[Formula: see text]O[Formula: see text]-dependent oxidation of ABTS and guaiacol are 10- and 100-fold higher, respectively, than those of wild type HTHP (HTHP[Formula: see text]. The [Formula: see text]/[Formula: see text] values of HTHP[Formula: see text] for both substrates are increased 30-fold relative to that of HTHP[Formula: see text]. Moreover, HTHP[Formula: see text] is capable of promoting catalytic sulfoxidation of thioanisole with H[Formula: see text]O[Formula: see text] with a turnover number ca. 2-fold higher than that of HTHP[Formula: see text]. The present findings demonstrate that proximal His ligation to the heme is significantly effective to increase the peroxidase activity in the HTHP matrix.

Mutable Properties of Nonheme Iron(III)-Iodosylarene Complexes Result in the Elusive Multiple-Oxidant Mechanism.

Although nonheme iron(III)-iodosylarene complexes present amazing oxidative efficiency and selectivity, the nature of such complexes and related oxidation mechanism are still unsolved after decades of experimental efforts. Density functional calculations were employed to explore the structure-reactivity relationship of the iron(III)-iodosylbenzene complex, [FeIII(tpena-) (PhIO)]2+ (1), in thioanisole sulfoxidation. Our theoretical work revealed that complex 1 can evolve into two resonance valence-bond electronic structures (a high-valent iron-oxo species and a monomeric PhIO species) in thioanisole sulfoxidation to present different reaction mechanisms (the novel bond-cleavage coupled electron transfer mechanism or the direct oxygen-atom transfer mechanism) as a response to different substrate attack orientations.

Substrate Sulfoxidation by an Iron(IV)-Oxo Complex: Benchmarking Computationally Calculated Barrier Heights to Experiment.

High-valent metal-oxo oxidants are common reactive species in synthetic catalysts as well as heme and nonheme iron enzymes. In general, they efficiently react with substrates through oxygen atom transfer, and for a number of cases, experimental rate constants have been determined. However, because these rate constants are generally measured in a polar solution, it has been found difficult to find computational methodologies to reproduce experimental trends and reactivities. In this work, we present a detailed computational study into para-substituted thioanisole sulfoxidation by a nonheme iron(IV)-oxo complex. A range of density functional theory methods and basis sets has been tested for their suitability to describe the reaction mechanism and compared with experimentally obtained free energies of activation. It is found that the enthalpy of activation is reproduced well, but all methods overestimate the entropy of activation by about 50%, for which we recommend a correction factor. The effect of solvent and dispersion on the barrier heights is explored both at the single-point level and also through inclusion in geometry optimizations, and particularly, solvent is seen as highly beneficial to reproduce experimental free energies of activation. Interestingly, in general, experimental trends and Hammett plots are reproduced well with almost all methods and procedures, and only a systematic error seems to apply for these chemical systems. Very good agreement between experiment and theory is found for a number of different methods, including B3LYP and PBE0, and procedures that are highlighted in the paper.

Spectroscopic characterization and reactivity studies of a mononuclear nonheme Mn(III)-hydroperoxo complex.

We report the first example of a mononuclear nonheme manganese(III)–hydroperoxo complex derived from protonation of an isolated manganese(III)–peroxo complex bearing an N-tetramethylated cyclam (TMC) ligand, [MnIII(TMC)(OOH)]2+. The MnIII-hydroperoxo intermediate is characterized with various spectroscopic methods as well as with density functional theory (DFT) calculations, showing the binding of a hydroperoxide ligand in an end-on fashion. The MnIII–hydroperoxo species is a competent oxidant in oxygen atom transfer (OAT) reactions, such as the oxidation of sulfides. The electrophilic character of the MnIII–hydroperoxo complex is demonstrated unambiguously in the sulfoxidation of para-substituted thioanisoles.

Neocarzinostatin-based hybrid biocatalysts for oxidation reactions.

An anionic iron(III)-porphyrin-testosterone conjugate 1-Fe has been synthesized and fully characterized. It has been further associated with a neocarzinostatin variant, NCS-3.24, to generate a new artificial metalloenzyme following the so-called 'Trojan Horse' strategy. This new 1-Fe-NCS-3.24 biocatalyst showed an interesting catalytic activity as it was found able to catalyze the chemoselective and slightly enantioselective (ee = 13%) sulfoxidation of thioanisole by H2O2. Molecular modelling studies show that a synergy between the binding of the steroid moiety and that of the porphyrin macrocycle into the protein binding site can explain the experimental results, indicating a better affinity of 1-Fe for the NCS-3.24 variant than testosterone and testosterone-hemisuccinate themselves. They also show that the Fe-porphyrin complex is sandwiched between the two subdomains of the protein providing with good complementarities. However, the artificial cofactor entirely fills the cavity and its metal ion remains widely exposed to the solvent which explains the moderate enantioselectivity observed. Some possible improvements in the "Trojan Horse" strategy for obtaining better catalysts of selective oxidations are presented.

Enhanced electron-transfer reactivity of nonheme manganese(IV)-oxo complexes by binding scandium ions.

One and two scandium ions (Sc(3+)) are bound strongly to nonheme manganese(IV)-oxo complexes, [(N4Py)Mn(IV)(O)](2+) (N4Py = N,N-bis(2-pyridylmethyl)-N-bis(2-pyridyl)methylamine) and [(Bn-TPEN)Mn(IV)(O)](2+) (Bn-TPEN = N-benzyl-N,N',N'-tris(2-pyridylmethyl)-1,2-diaminoethane), to form Mn(IV)(O)-(Sc(3+))1 and Mn(IV)(O)-(Sc(3+))2 complexes, respectively. The binding of Sc(3+) ions to the Mn(IV)(O) complexes was examined by spectroscopic methods as well as by DFT calculations. The one-electron reduction potentials of the Mn(IV)(O) complexes were markedly shifted to a positive direction by binding of Sc(3+) ions. Accordingly, rates of the electron transfer reactions of the Mn(IV)(O) complexes were enhanced as much as 10(7)-fold by binding of two Sc(3+) ions. The driving force dependence of electron transfer from various electron donors to the Mn(IV)(O) and Mn(IV)(O)-(Sc(3+))2 complexes was examined and analyzed in light of the Marcus theory of electron transfer to determine the reorganization energies of electron transfer. The smaller reorganization energies and much more positive reduction potentials of the Mn(IV)(O)-(Sc(3+))2 complexes resulted in remarkable enhancement of the electron-transfer reactivity of the Mn(IV)(O) complexes. Such a dramatic enhancement of the electron-transfer reactivity of the Mn(IV)(O) complexes by binding of Sc(3+) ions resulted in the change of mechanism in the sulfoxidation of thioanisoles by Mn(IV)(O) complexes from a direct oxygen atom transfer pathway without metal ion binding to an electron-transfer pathway with binding of Sc(3+) ions.

Amino Alcohol-Derived Reduced Schiff Base VIVO and VV Compounds as Catalysts for Asymmetric Sulfoxidation of Thioanisole with Hydrogen Peroxide

We report the synthesis and characterization of several amino alcohol-derived reduced Schiff base ligands (AORSB) and the corresponding V(IV)O and V(V) complexes. Some of the related Schiff base variants (amino alcohol derived Schiff base = AOSB) were also prepared and characterized. With some exceptions, all compounds are formulated as dinuclear compounds {V(IV)O(L)}(2) in the solid state. Suitable crystals for X-ray diffraction were obtained for two of the AORSB compounds, as well as a rare X-ray structure of a chiral V(IV)O compound, which revealed a dinuclear {V(IV)O(AOSB)}(2) structure with a rather short V-V distance of 3.053(9) Å. Electron paramagnetic resonance (EPR), (51)V NMR, and density functional theory (DFT) studies were carried out to identify the intervenient species prior to and during catalytic reactions. The quantum-chemical DFT calculations were important to determine the more stable isomers in solution, to explain the EPR data, and to assign the (51)V NMR chemical shifts. The V(AORSB) and V(AOSB) complexes were tested as catalysts in the oxidation of thioanisole, with H(2)O(2) as the oxidant in organic solvents. In general, high conversions of sulfoxide were obtained. The V(AOSB) systems exhibited greater activity and enantioselectivity than their V(AORSB) counterparts. Computational and spectroscopic studies were carried out to assist in the understanding of the mechanistic aspects and the reasons behind such marked differences in activity and enantioselectivity. The quantum-chemical calculations are consistent with experimental data in the assessment of the differences in catalytic activity between V(AOSB) and V(AORSB) peroxido variants because the V(AORSB) peroxido transition states correspond to ca. 22 kJ/mol higher energy activation barriers than their V(AOSB) counterparts.

Asymmetric Sulfoxidation of Thioanisole by Helical Ti(IV) Salan Catalysts

Abstract A new helix-directing salan ligand (R,R)-2 with the (1R,2R)-diaminocyclohexyl backbone and benz[a]anthryl sidearms was synthesized by borohydride reduction of the corresponding salen ligand. Formylation and reduction of (R,R)-2 yielded the N-Me counterpart, (R,R)-3. Complexation of these flexible ligands to TiCl4 produced the [TiCl2(salan)] complexes (R,R)-4 and (R,R)-5, which were characterized by NMR, IR, and HRMS techniques. The complexes were tested as catalysts for the asymmetric sulfoxidation of thioanisole with cumene hydroperoxide and hydrogen peroxide as the oxidants. Modest selectivity was observed, with the N-H salan complex showing somewhat better chiral induction.

A Chromium(III)–Superoxo Complex in Oxygen Atom Transfer Reactions as a Chemical Model of Cysteine Dioxygenase

Metal-superoxo species are believed to play key roles in oxygenation reactions by metalloenzymes. One example is cysteine dioxygenase (CDO) that catalyzes the oxidation of cysteine with O(2), and an iron(III)-superoxo species is proposed as an intermediate that effects the sulfoxidation reaction. We now report the first biomimetic example showing that a chromium(III)-superoxo complex bearing a macrocyclic TMC ligand, [Cr(III)(O(2))(TMC)(Cl)](+), is an active oxidant in oxygen atom transfer (OAT) reactions, such as the oxidation of phosphine and sulfides. The electrophilic character of the Cr(III)-superoxo complex is demonstrated unambiguously in the sulfoxidation of para-substituted thioanisoles. A Cr(IV)-oxo complex, [Cr(IV)(O)(TMC)(Cl)](+), formed in the OAT reactions by the chromium(III)-superoxo complex, is characterized by X-ray crystallography and various spectroscopic methods. The present results support the proposed oxidant and mechanism in CDO, such as an iron(III)-superoxo species is an active oxidant that attacks the sulfur atom of the cysteine ligand by the terminal oxygen atom of the superoxo group, followed by the formation of a sulfoxide and an iron(IV)-oxo species via an O-O bond cleavage.

Proton-Promoted Oxygen Atom Transfer vs Proton-Coupled Electron Transfer of a Non-Heme Iron(IV)-Oxo Complex

Sulfoxidation of thioanisoles by a non-heme iron(IV)-oxo complex, [(N4Py)Fe(IV)(O)](2+) (N4Py = N,N-bis(2-pyridylmethyl)-N-bis(2-pyridyl)methylamine), was remarkably enhanced by perchloric acid (70% HClO(4)). The observed second-order rate constant (k(obs)) of sulfoxidation of thioaniosoles by [(N4Py)Fe(IV)(O)](2+) increases linearly with increasing concentration of HClO(4) (70%) in acetonitrile (MeCN)at 298 K. In contrast to sulfoxidation of thioanisoles by [(N4Py)Fe(IV)(O)](2+), the observed second-order rate constant (k(et)) of electron transfer from one-electron reductants such as [Fe(II)(Me(2)bpy)(3)](2+) (Me(2)bpy = 4,4-dimehtyl-2,2'-bipyridine) to [(N4Py)Fe(IV)(O)](2+) increases with increasing concentration of HClO(4), exhibiting second-order dependence on HClO(4) concentration. This indicates that the proton-coupled electron transfer (PCET) involves two protons associated with electron transfer from [Fe(II)(Me(2)bpy)(3)](2+) to [(N4Py)Fe(IV)(O)](2+) to yield [Fe(III)(Me(2)bpy)(3)](3+) and [(N4Py)Fe(III)(OH(2))](3+). The one-electron reduction potential (E(red)) of [(N4Py)Fe(IV)(O)](2+) in the presence of 10 mM HClO(4) (70%) in MeCN is determined to be 1.43 V vs SCE. A plot of E(red) vs log[HClO(4)] also indicates involvement of two protons in the PCET reduction of [(N4Py)Fe(IV)(O)](2+). The PCET driving force dependence of log k(et) is fitted in light of the Marcus theory of outer-sphere electron transfer to afford the reorganization of PCET (λ = 2.74 eV). The comparison of the k(obs) values of acid-promoted sulfoxidation of thioanisoles by [(N4Py)Fe(IV)(O)](2+) with the k(et) values of PCET from one-electron reductants to [(N4Py)Fe(IV)(O)](2+) at the same PCET driving force reveals that the acid-promoted sulfoxidation proceeds by one-step oxygen atom transfer from [(N4Py)Fe(IV)(O)](2+) to thioanisoles rather than outer-sphere PCET.

ChemInform Abstract: Asymmetric Oxidation of Sulfides with H2O2 Catalyzed by Titanium Complexes of Schiff Bases Bearing a Dicumenyl Salicylidenyl Unit.

The sterically hindered Schiff bases (L3–L5), prepared from 3,5-dicumenyl salicylaldehyde and chiral amino alcohols, were used in combination with Ti(OiPr)4 for asymmetric oxidation of aryl methyl sulfides with H2O2 as terminal oxidant. Among the ligands L3–L5, L4 with a tert-butyl group in the chiral carbon of the amino alcohol moiety gave the best result with 89% yield and 73% ee for the sulfoxidation of thioanisole under optimal conditions [with 1 mol% of Ti(OiPr)4 in a molar ratio of 100:1:1.2:120 for sulfide:Ti(OiPr)4:ligand:H2O2 in CH2Cl2 at 0 °C for 3 h]. The reaction afforded good yield (84%) with a moderate enantioselectivity (62% ee) even with a lower catalyst loading from 1.0 to 0.5 mol%. The oxidations of methyl 4-bromophenyl sulfide and methyl 4-methoxyphenyl sulfide with H2O2 catalyzed by the Ti(OiPr)4–L4 system gave 79–84% yields and 54–59% ee of the corresponding sulfoxides in CH2Cl2 at 20 °C. The chiral induction capability of the cumenyl-modified sterically hindered Schiff bases for sulfoxidation was compared with the conventional Schiff bases bearing tert-butyl groups at the 3,5-positions of the salicylidenyl unit. Copyright © 2011 John Wiley & Sons, Ltd.

Metal Ion Effect on the Switch of Mechanism from Direct Oxygen Transfer to Metal Ion-Coupled Electron Transfer in the Sulfoxidation of Thioanisoles by a Non-Heme Iron(IV)−Oxo Complex

The mechanism of sulfoxidation of thioaniosoles by a non-heme iron(IV)-oxo complex is switched from direct oxygen transfer to metal ion-coupled electron transfer by the presence of Sc(3+). The switch in the sulfoxidation mechanism is dependent on the one-electron oxidation potentials of thioanisoles. The rate of sulfoxidation is accelerated as much as 10(2)-fold by the addition of Sc(3+).

Asymmetric oxidation of sulfides with H2O2 catalyzed by titanium complexes of Schiff bases bearing a dicumenyl salicylidenyl unit

The sterically hindered Schiff bases (L3–L5), prepared from 3,5-dicumenyl salicylaldehyde and chiral amino alcohols, were used in combination with Ti(OiPr)4 for asymmetric oxidation of aryl methyl sulfides with H2O2 as terminal oxidant. Among the ligands L3–L5, L4 with a tert-butyl group in the chiral carbon of the amino alcohol moiety gave the best result with 89% yield and 73% ee for the sulfoxidation of thioanisole under optimal conditions [with 1 mol% of Ti(OiPr)4 in a molar ratio of 100:1:1.2:120 for sulfide:Ti(OiPr)4:ligand:H2O2 in CH2Cl2 at 0 °C for 3 h]. The reaction afforded good yield (84%) with a moderate enantioselectivity (62% ee) even with a lower catalyst loading from 1.0 to 0.5 mol%. The oxidations of methyl 4-bromophenyl sulfide and methyl 4-methoxyphenyl sulfide with H2O2 catalyzed by the Ti(OiPr)4–L4 system gave 79–84% yields and 54–59% ee of the corresponding sulfoxides in CH2Cl2 at 20 °C. The chiral induction capability of the cumenyl-modified sterically hindered Schiff bases for sulfoxidation was compared with the conventional Schiff bases bearing tert-butyl groups at the 3,5-positions of the salicylidenyl unit. Copyright © 2011 John Wiley & Sons, Ltd.

Non-covalent modification of the active site of cytochrome P450 for inverting the stereoselectivity of monooxygenation

The enantioselectivity in the sulfoxidation of thioanisole catalyzed by cytochrome P450BSβ with a decoy molecule, a dummy molecule of the natural substrate, can be inverted by changing the structure of the decoy molecule. The methodology demonstrated herein shows the potential for controlling the stereoselectivity of biocatalysts without any mutagenesis.

Reaction of Singlet Oxygen with Thioanisole in Ionic Liquid−Acetonitrile Binary Mixtures

A study of the reaction of thioanisole with singlet oxygen in different ionic liquid-acetonitrile binary mixtures has shown that ILs are able to accelerate the thioanisole sulfoxidation when used as additives. With imidazolium ILs, the maximum efficiency is reached at x(IL) ∼ 0.1-0.2, whereas for the pyrrolidinium IL a plateau is reached. These results are discussed in terms of the ILs' tendency to form ionic aggregates and of differences in sulfoxidation reaction mechanism.

Vanadium Diaminebis(phenolate) Complexes: Syntheses, Structures, and Reactivity in Sulfoxidation Catalysis

Vanadium diaminebis(phenolate) complexes of the general formulas [LVCl(THF)] (L = Me(2)NCH(2)CH(R)N(CH(2)-2-O-3,5-C(6)H(2)(t)Bu(2))(2), where R = H, Me) and [LV(O)X] [X = Cl; R = H (2), Me (3), O(i)Pr (4), (mu-O)V(O)L (5)] are described. All compounds display octahedral geometry and trans-O(Ph) coordination. For compounds 2, 3, and 5, only one isomer, presenting the V=O ligand trans to the tripodal nitrogen, was formed, while for 4, two isomers were observed by NMR in solution. The UV-vis and circular dichroism spectra of 2 and 3 display very intense charge-transfer transition bands from the phenolate donors to the vanadium, which are in agreement with the (51)V low-field shifts observed. All vanadium(V) complexes were tested as thioanisole sulfoxidation catalysts, revealing very high selectivity when H(2)O(2) was used as the oxidant. However, no enantioselectivity was observed even when enantiopure 3 was used as the catalyst precursor. (1)H and (51)V NMR studies were conducted for the reactions of 2 with aqueous solutions of H(2)O(2) in methanol-d(4) and in acetonitrile-d(3); 2 reacts with the solvents, leading to [LV(O)OMe], by replacement of Cl by MeO in methanol, and to a new vanadium aminebis(phenolate) complex, where the dimethylamine fragment of the original ligand L was replaced by CH(3)CN. In either case, (51)V NMR spectra suggest the formation of peroxovanadium species upon the addition of a H(2)O(2) solution. The subsequent addition of thioanisole to the methanol-d(4) solution leads to regeneration of the original complex.

Recyclable Nanobiocatalyst for Enantioselective Sulfoxidation: Facile Fabrication and High Performance of Chloroperoxidase-Coated Magnetic Nanoparticles with Iron Oxide Core and Polymer Shell

Magnetic nanoparticles (MNPs) with a core diameter of 30 nm comprising several iron oxide crystals, a poly(glycidyl methacrylate) (PGMA) shell with a thickness of 30 nm, and a surface coated with chloroperoxidase (CPO) were facilely fabricated as a nanobiocatalyst for asymmetric sulfoxidation. The covalently bound CPO did not change the original conformation of the active site and showed the same catalytic activity and enantioselectivity as free CPO for the sulfoxidation of thioanisole to produce (R)-methyl phenyl sulfoxide in >99% ee. The thick PGMA shell significantly increased the stability of the nanobiocatalyst: no loss of the sulfoxidation activity was observed after 11 times of recycling and reuse of the catalyst. Thus, the nanobiocatalyst fabricated here showed the best performance among nanosized biocatalyst particles regarding both the retaining of free enzyme activity and the recycling of catalyst. This is also the first example of a nanobiocatalyst for asymmetric oxidation, and the concept could be generally applicable for fabricating active and recyclable nanobiocatalysts.