Enantioselective conversion of α-arylnitriles by Klebsiella oxytoca

Ewert, Christian; Lutz-Wahl, Sabine; Fischer, Lutz

doi:10.1016/j.tetasy.2008.11.014

Cited by 15 publications

(7 citation statements)

References 18 publications

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“…This is the first case of a nitrile hydratase that is enantioselective towards bulky aliphatic substrates. Ewert et al (2008) reported bacteria isolated from K. oxytoca which could carry out the enantioselective conversion of racemic-arylnitriles to their amide products (Figure 4). (S)-enantioselective nitrile hydratase and a putative (S)-selective amidase was induced and produced in the isolated microorganism.…”

Section: Rhodococcus Equi A4mentioning

confidence: 99%

Stereoselective nitrile hydratase

Shen¹,

Du²,

Gao³

et al. 2012

Afr. J. Microbiol. Res.

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Nitrile hydratase, catalyzing the hydration reaction of nitrile to amides, is an important enzyme which has been used in the industrial production. Various studies on nitrile hydratase revealed its crystal structure and also proposed some hypothesis of its catalytic mechanism. Recent reports suggested the stereoselectivity of nitrile hydratase, which is regarded as a potential character to enrich its application. However, the isolated organisms are limited as only few genera identified contain this special stereoselective enzyme. This review described the corresponding strain for producing the enzyme, the structure and catalytic mechanism for stereoselectivity of the enzyme.

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Section: Rhodococcus Equi A4mentioning

confidence: 99%

Stereoselective nitrile hydratase

Shen¹,

Du²,

Gao³

et al. 2012

Afr. J. Microbiol. Res.

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“…Most published works on stereoselective enzymatic conversions of racemic α‐aminonitriles have dealt with the direct production of optical pure α‐amino acids via a nitrilase‐catalyzed hydrolysis of α‐aminonitriles, forming α‐amino acids such as ( S )‐alanine,1 ( S )‐leucine,2 and ( S )‐phenylglycine 3. Only very little work has been done on the conversion of mainly phenylglycinonitrile to ( S )‐ or ( R )‐phenylglycine by kinetic resolution (KR) in from 25% up to 50% yield via phenylglycinamide with a nitrile hydratase‐amidase system 4–7. For example, Ewert et al4 reported that nitrile hydratase (NHase) from Klebsiella oxytoca preferentially converted the S ‐enantiomer to ( S )‐phenylglycinamide with an E value of 7.8, and in the presence of an S ‐stereoselective amidase, 1 mM ( RS )‐phenylglycinonitrile was converted to ( S )‐phenylglycine with >99% ee and ( R )‐phenylglycinamide with >99% ee by KR.…”

Section: Methodsmentioning

confidence: 99%

“…Only very little work has been done on the conversion of mainly phenylglycinonitrile to ( S )‐ or ( R )‐phenylglycine by kinetic resolution (KR) in from 25% up to 50% yield via phenylglycinamide with a nitrile hydratase‐amidase system 4–7. For example, Ewert et al4 reported that nitrile hydratase (NHase) from Klebsiella oxytoca preferentially converted the S ‐enantiomer to ( S )‐phenylglycinamide with an E value of 7.8, and in the presence of an S ‐stereoselective amidase, 1 mM ( RS )‐phenylglycinonitrile was converted to ( S )‐phenylglycine with >99% ee and ( R )‐phenylglycinamide with >99% ee by KR. These KR of α‐aminonitriles only leave unreacted substrate or by‐product in the reaction mixture.…”

Section: Methodsmentioning

confidence: 99%

Dynamic Kinetic Resolution of α‐Aminonitriles to Form Chiral α‐Amino Acids

2011

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Abstract:We have succeeded in the enzymatic synthesis of (R)-a-aminobutyric acid from racemic aaminobutyronitrile. This has been demonstrated by the use of non-stereoselective nitrile hydratase (NHase) from Rhodococcus opacus 71D, d-aminopeptidase from Ochrobactrum anthropi C1-38 and a-amino-e-caprolactam (ACL) racemase from Achromobacter obae. Racemic a-aminobutyronitrile was completely converted in 6 h at 30 8C to (R)-aaminobutyric acid whose optical purity was more than 99%. (S)-a-Aminobutyric acid was also synthesized from a-aminobutyronitrile by NHase, ACL racemase and l-amino acid amidase from Brevundimonas diminuta TPU 5720. In a similar manner, other (R)-or (S)-a-amino acids with more than 97.5% ee could be synthesized from the corresponding a-aminonitriles. This is the first report on the dynamic kinetic resolution (DKR) of a-aminonitriles to form chiral a-amino acids. The key enzyme in this DKR is non-stereoselective NHase, which had been newly screened from soil samples, and its gene cloned.

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“…The low enantioselectivity of nitrile hydrolyzing enzymes was a hurdle in developing efficient approaches for resolution of racemic nitriles. Notwithstanding, numerous reports indicated that nitrile converting enzymes can mediate enantioselective kinetic resolution − and dynamic kinetic resolution − through hydrolysis of nitriles; however, enzymes are also found to be regioselective which prefer a single nitrile group of dinitrile compound. , …”

Section: Introductionmentioning

confidence: 99%

Enantioselective Enzymatic Hydrolysis of rac-Mandelonitrile to R-Mandelamide by Nitrile Hydratase Immobilized on Poly(vinyl alcohol)/Chitosan–Glutaraldehyde Support

Pawar

Yadav

2014

Ind. Eng. Chem. Res.

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Nitriles, amides and carboxylic acids have varied applications in active pharmaceutical intermediate (API), drug and chemical industry, and particularly in the synthesis of pure enantiomers of chiral compounds. The chemical hydrolysis of nitrile compounds is well studied, but it necessitates harsh conditions along with the protection of sensitive functional groups, which on deprotection leads to generation of a large amount of byproducts. Immobilization of nitrile hydratase using a novel support reduces the cost and allows green processes. In this work, enantioselective hydrolysis of rac-mandelonitrile was studied using poly(vinyl alcohol) (PVA)/chitosan−glutaraldehyde cross-linked Rhodococcus rhodochrous ATCC BAA-870 nitrile hydratase (NHase). Immobilized NHase converted rac-mandelonitrile to (R)-amide by dynamic kinetic resolution with enantiomeric excess (ee) up to 81%. The temperature of 40 °C and pH 8 were found to be optimum for the enantioselective nitrile hydrolysis. In the presence of various cosolvents, immobilized NHase showed higher retention of activity in methanol compared to other cosolvents. The kinetic constants for free and immobilized enzyme were obtained from the Lineweaver−Burk plot. The immobilized NHase was found to be reusable up to nine successive batch reactions.

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Enantioselective conversion of α-arylnitriles by Klebsiella oxytoca

Cited by 15 publications

References 18 publications

Stereoselective nitrile hydratase

Stereoselective nitrile hydratase

Dynamic Kinetic Resolution of α‐Aminonitriles to Form Chiral α‐Amino Acids

Enantioselective Enzymatic Hydrolysis of rac-Mandelonitrile to R-Mandelamide by Nitrile Hydratase Immobilized on Poly(vinyl alcohol)/Chitosan–Glutaraldehyde Support

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