Transfer hydrogenations catalyzed by streptavidin-hosted secondary amine organocatalysts

Santi, Nicolò; Morrill, Louis C.; Świderek, Katarzyna; Moliner, Vicent; Luk, Louis Y. P.

doi:10.1039/d0cc08142f

Cited by 16 publications

(35 citation statements)

References 39 publications

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“…Whereas 1-3 are water soluble, transfer hydrogenation with NADPH by these secondary amines in aqueous buffer was not observed. This is also the case for the protein-hosted secondary amines presented here and previously 11 . It is likely that the dinucleotide hinders the dihydronicotinamide motif from approaching the intermediate for reactions.…”

Section: Resultssupporting

confidence: 81%

“…Organocatalysis has tremendous potentials for its applications in arti cial enzyme design [1][2][3][4] . By hosting small organocatalytic motifs proteins can catalyse reactions with "new-to-nature" mechanisms, and various methods have been reported to generate protein-based organocatalysts [5][6][7][8][9][10][11][12][13][14][15] . However, a generic approach that recruits natural molecules as reagents is yet to be established.…”

Section: Introductionmentioning

confidence: 99%

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NADPH-dependent Secondary Amine Organocatalysis hosted by a Nucleotide-binding Domain

Williams¹,

Tsai²,

Luk³

2021

Preprint

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The concept of organocatalysis has been applied to facilitate “new-to-nature” reaction modes via artificial enzyme design. However, it remains challenging to recruit structurally complex natural molecules as synthetic reagents. Here, we have reported a generic design strategy that allows generation of a NADPH-dependent hybrid catalyst whose action is orchestrated by a secondary amine; this system recruits a reaction mode not commonly seen among enzymes, whilst involving an intricate cofactor that cannot be used by existing organocatalysts. A secondary amine organocatalytic motif was incorporated into protein scaffolds as an unnatural amino acid by expansion of the genetic code. When introduced into the multidrug binding protein LmrR, a hybrid catalyst accepting α,β-unsaturated carbonyl substrates for transfer hydrogenation was established but was confined to the much-simplified biomimetic benzyl dihydronicotinamide (BNAH). Conversely, dihydrofolate reductase (DHFR) contains a nucleotide binding domain and can be converted into a hybrid catalyst that favourably uses NADPH for reaction, thus highlighting the importance of choosing an appropriate scaffold. The DHFR-hosted system tolerates a range of aldehyde substrates and can be coupled with an enzymatic NADPH regeneration scheme. The presented engineering approach can be readily extended to other protein scaffolds for use of different natural molecules in non-natural reaction modes.

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Section: Resultssupporting

confidence: 81%

Section: Introductionmentioning

confidence: 99%

NADPH-dependent Secondary Amine Organocatalysis hosted by a Nucleotide-binding Domain

Williams¹,

Tsai²,

Luk³

2021

Preprint

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“…We chose the conversion of cinnamaldehyde 4 to its reduced counterpart 5 as the model reaction (Fig. 3) because the streptavidin (Sav)-hosted pyrrolidine was shown to be able to catalyze this reaction, 23 and hence direct comparison among the protein-based catalytic systems can be made. BNAH, unlike other biomimetics such as Hantzsch ester, is soluble in aqueous buffers and thus was tested as the hydride donor.…”

Section: Resultsmentioning

confidence: 99%

“…BNAH, unlike other biomimetics such as Hantzsch ester, is soluble in aqueous buffers and thus was tested as the hydride donor. 23 Conversion of the reaction was estimated using a gas chromatography-mass spectrometry (GC-MS) setup as previously described (see SI). 41 Though containing seven lysine residues and a free Nterminal amino group, the wild-type LmrR could only catalyze less than 3% of conversion implying minimal activity (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…[17][18][19][20] In the second approach, pyrrolidines covalently linked to biotin were introduced to streptavidin (Sav) affording a protein-hosted secondary amine catalytic system. [21][22][23] These protein catalysts could catalyze various types of reactions, including conjugate addition, [19][20][21] aldol condensation, 18,22 transfer hydrogenation 23 and epoxidation. 24 However, since there are only a few proteins that contain a N-terminal proline within their cavity 3,6 and also only a few that bind biotin with signi cant a nity, [25][26] the choice of protein templates for hosting secondary amine is limited.…”

Section: Introductionmentioning

confidence: 99%

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Break the template boundary: Test of different protein scaffolds by genetic code expansion resulted in NADPH-dependent secondary amine catalysis

Williams

Tsai

Luk

2021

Preprint

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Here, incorporation of secondary amine by genetic code expansion was used to expand the potential protein templates for artificial enzyme design. Pyrrolysine analogue containing a D-proline could be stably incorporated into proteins, including the multidrug-binding LmrR and nucleotide-binding dihydrofolate reductase (DHFR). Both modified scaffolds were catalytically active, mediating transfer hydrogenation with a relaxed substrate scope. The protein templates played a distinctive role in that, while the LmrR variants were confined to the biomimetic BNAH as the hydride source, the optimal DHFR variant favorably used the pro-R hydride from NADPH for reactions. Due to the cofactor compatibility, the DHFR secondary amine catalysis could also be coupled to an enzymatic recycling scheme. This work has illustrated the unique advantages of using proteins as hosts, and thus the presented concept is expected to find uses in enabling tailored secondary amine catalysis.

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Unlocking New Reactivities in Enzymes by Iminium Catalysis

Poelarends

2022

Angewandte Chemie

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The application of biocatalysis in conquering challenging synthesis requires the constant input of new enzymes. Developing novel biocatalysts by absorbing catalysis modes from synthetic chemistry has yielded fruitful new‐to‐nature enzymes. Organocatalysis was originally bio‐inspired and has become the third pillar of asymmetric catalysis. Transferring organocatalytic reactions back to enzyme platforms is a promising approach for biocatalyst creation. Herein, we summarize recent developments in the design of novel biocatalysts that adopt iminium catalysis, a fundamental branch in organocatalysis. By repurposing existing enzymes or constructing artificial enzymes, various biocatalysts for iminium catalysis have been created and optimized via protein engineering to promote valuable abiological transformations. Recent advances in iminium biocatalysis illustrate the power of combining chemomimetic biocatalyst design and directed evolution to generate useful new‐to‐nature enzymes.

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Transfer hydrogenations catalyzed by streptavidin-hosted secondary amine organocatalysts

Abstract: Streptavidin-based secondary amine enables organocatalytic hydride reduction.

Cited by 16 publications

References 39 publications

NADPH-dependent Secondary Amine Organocatalysis hosted by a Nucleotide-binding Domain

NADPH-dependent Secondary Amine Organocatalysis hosted by a Nucleotide-binding Domain

Break the template boundary: Test of different protein scaffolds by genetic code expansion resulted in NADPH-dependent secondary amine catalysis

Unlocking New Reactivities in Enzymes by Iminium Catalysis

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