Reductive aminations by imine reductases: from milligrams to tons

Gilio, A.K.; Thorpe, Thomas; Turner, Nicholas J.; Grogan, Gideon

doi:10.1039/d2sc00124a

Cited by 45 publications

(41 citation statements)

References 79 publications

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“…In such cases where evidence has been provided of the enzyme catalyzing both chemical steps at near or equimolar ratios of ketone and amine substrates, this subset of IREDs have also been termed “reductive aminases” (RedAms) (Scheme ). − …”

Section: Introductionmentioning

confidence: 99%

A Reductive Aminase Switches to Imine Reductase Mode for a Bulky Amine Substrate

et al. 2023

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Imine reductases (IREDs) catalyze the asymmetric reduction of cyclic imines, but also in some cases the coupling of ketones and amines to form secondary amine products in an enzymecatalyzed reductive amination (RedAm) reaction. Enzymatic RedAm reactions have typically used small hydrophobic amines, but many interesting pharmaceutical targets require that larger amines be used in these coupling reactions. Following the identification of IR77 from Ensifer adhaerens as a promising biocatalyst for the reductive amination of cyclohexanone with pyrrolidine, we have characterized the ability of this enzyme to catalyze couplings with larger bicyclic amines such as isoindoline and octahydrocyclopenta(c)pyrrole. By comparing the activity of IR77 with reductions using sodium cyanoborohydride in water, it was shown that, while the coupling of cyclohexanone and pyrrolidine involved at least some element of reductive amination, the amination with the larger amines likely occurred ex situ, with the imine recruited from solution for enzyme reduction. The structure of IR77 was determined, and using this as a basis, structureguided mutagenesis, coupled with point mutations selecting improving amino acid sites suggested by other groups, permitted the identification of a mutant A208N with improved activity for amine product formation. Improvements in conversion were attributed to greater enzyme stability as revealed by X-ray crystallography and nano differential scanning fluorimetry. The mutant IR77-A208N was applied to the preparative scale amination of cyclohexanone at 50 mM concentration, with 1.2 equiv of three larger amines, in isolated yields of up to 93%.

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Section: Introductionmentioning

confidence: 99%

A Reductive Aminase Switches to Imine Reductase Mode for a Bulky Amine Substrate

et al. 2023

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“…A choline oxidase variant, for example, is a broad spectrum primary alcohol oxidase 146 and a GOase variant catalysed the ammoxidation of primary alcohols to nitriles. 147 Enantiopure chiral primary amines are also key intermediates in the synthesis of a wide variety of pharmaceuticals and can be produced by a suite of biocatalytic methods [148][149][150] using amine oxidases (AOs), amine dehydrogenases (AmDHs) and imine reductases (IREDs). A synthesis of Boceprevir, for example, involved an AO catalysed desymmetrisation as the key step.…”

Section: The Ever Broadening Scope Of Biocatalysismentioning

confidence: 99%

“…Enantiopure chiral primary amines are also key intermediates in the synthesis of a wide variety of pharmaceuticals and can be produced by a suite of biocatalytic methods 148–150 using amine oxidases (AOs), amine dehydrogenases (AmDHs) and imine reductases (IREDs). A synthesis of Boceprevir, for example, involved an AO catalysed desymmetrisation as the key step.…”

Section: Biocatalysis Is Sustainable and Greenmentioning

confidence: 99%

The E factor at 30: a passion for pollution prevention

Sheldon

2023

Green Chem.

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“…Recent reviews have highlighted the application of IREDs in the synthesis of several drugs and pharmaceutical intermediates, including alkaloids such as tetrahydroisoquinolines (THIQs). [21,22] Many THIQs are naturally synthesised by plants and the scaffold has an important role in medicinal chemistry due to the wide range of pharmacological properties exhibited, such as anti-HIV, antitumor, anti-inflammatory, and use as bronchodilators and antibiotics. [23][24][25][26] Different biocatalytic routes to access THIQs have been studied using monoamine oxidases, norcoclaurine synthases and the berberine bridge enzyme.…”

Section: Introductionmentioning

confidence: 99%

The Discovery of Imine Reductases and their Utilisation for the Synthesis of Tetrahydroisoquinolines

et al. 2023

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Imine reductases (IREDs) are NADPH-dependent enzymes with significant biocatalytic potential for the synthesis of primary, secondary, and tertiary chiral amines. Their applications include the reduction of cyclic imines and the reductive amination of prochiral ketones. In this study, twenty-nine novel IREDs were revealed through genome mining. Imine reductase activities were screened at pH 7 and 9 and in presence of either NADPH or NADH; some IREDs showed good activities at both pHs and were able to accept both cofactors. IREDs with Asn and Glu at the key 187 residue showed preference for NADH. IREDs were also screened against a series of dihydroisoquinolines to synthesise tetrahydroisoquinolines (THIQs), bioactive alkaloids with a wide range of therapeutic properties. Selected IREDs showed high stereoselectivity, as well high THIQ yields (> 90 %) when coupled to a glucose-6-phosphate dehydrogenase for NADPH cofactor recycling.

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Reductive aminations by imine reductases: from milligrams to tons

Abstract: The synthesis of secondary and tertiary amines through the reductive amination of carbonyl compounds is one of the most significant reactions in synthetic chemistry. Asymmetric reductive amination for the formation...

Cited by 45 publications

References 79 publications

A Reductive Aminase Switches to Imine Reductase Mode for a Bulky Amine Substrate

A Reductive Aminase Switches to Imine Reductase Mode for a Bulky Amine Substrate

The E factor at 30: a passion for pollution prevention

The Discovery of Imine Reductases and their Utilisation for the Synthesis of Tetrahydroisoquinolines

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