Recent advances in enzymatic oxidation of alcohols

Liu, Ji; Wu, Shuke; Li, Zhi

doi:10.1016/j.cbpa.2017.12.001

Cited by 78 publications

(64 citation statements)

References 72 publications

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“…Biocatalysis by P2O can bypassc hemical oxidations of alcohols, which typically use toxic metal catalysts, generate problematic by-products and require many synthetic steps of group protection/deprotection. [108][109][110] Recently, the engineeredP 2O has been demonstrated to be av aluable biocatalyst for one-pot conversion of l-arabinose into l-ribulose. [111]…”

Section: Discussionmentioning

confidence: 99%

The Mechanism of Sugar C−H Bond Oxidation by a Flavoprotein Oxidase Occurs by a Hydride Transfer Before Proton Abstraction

Wongnate

Surawatanawong

Chuaboon

et al. 2019

Chemistry A European J

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Understanding the reaction mechanism underlying the functionalization of C−H bonds by an enzymatic process is one of the most challenging issues in catalysis. Here, combined approaches using density functional theory (DFT) analysis and transient kinetics were employed to investigate the reaction mechanism of C−H bond oxidation in d‐glucose, catalyzed by the enzyme pyranose 2‐oxidase (P2O). Unlike the mechanisms that have been conventionally proposed, our findings show that the first step of the C−H bond oxidation reaction is a hydride transfer from the C2 position of d‐glucose to N5 of the flavin to generate a protonated ketone sugar intermediate. The proton is then transferred from the protonated ketone intermediate to a conserved residue, His548. The results show for the first time how specific interactions around the sugar binding site promote the hydride transfer and formation of the protonated ketone intermediate. The DFT results are also consistent with experimental results including the enthalpy of activation obtained from Eyring plots, as well as the results of kinetic isotope effect and site‐directed mutagenesis studies. The mechanistic model obtained from this work may also be relevant to other reactions of various flavoenzyme oxidases that are generally used as biocatalysts in biotechnology applications.

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Section: Discussionmentioning

confidence: 99%

The Mechanism of Sugar C−H Bond Oxidation by a Flavoprotein Oxidase Occurs by a Hydride Transfer Before Proton Abstraction

Wongnate

Surawatanawong

Chuaboon

et al. 2019

Chemistry A European J

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“…The selective oxidation of primary and secondary alcohols to aldehydes and ketones,r espectively,i sakey reaction in organic synthesis. These reactions were traditionally carriedo ut with stoichiometric amounts of inorganic oxidants, such as chromium VI reagents, but efficient chemocatalytic [90] and biocatalytic methods [91] have grown in importance in recent years.…”

Section: Alcohol Oxidationsmentioning

confidence: 99%

Broadening the Scope of Biocatalysis in Sustainable Organic Synthesis

2019

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This Review is aimed at synthetic organic chemists who may be familiar with organometallic catalysis but have no experience with biocatalysis, and seeks to provide an answer to the perennial question: if it is so attractive, why wasn't it extensively used in the past? The development of biocatalysis in industrial organic synthesis is traced from the middle of the last century. Advances in molecular biology in the last two decades, in particular genome sequencing, gene synthesis and directed evolution of proteins, have enabled remarkable improvements in scope and substantially reduced biocatalyst development times and cost contributions. Additionally, improvements in biocatalyst recovery and reuse have been facilitated by developments in enzyme immobilization technologies. Biocatalysis has become eminently competitive with chemocatalysis and the biocatalytic production of important pharmaceutical intermediates, such as enantiopure alcohols and amines, has become mainstream organic synthesis. The synthetic space of biocatalysis has significantly expanded and is currently being extended even further to include new‐to‐nature biocatalytic reactions.

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“…[10] Nevertheless, in the oxidative mode, the ADHs have been more commonly used than AOXs, since there are more discovered enzymes with activity and selectivity towards molecules of interest. [11,12] Nevertheless, in the oxidative direction, ADHs require NAD(P) + as an electron acceptor, which is an expensive cofactor and therefore needs to be regenerated to achieve an economically feasible process. [13] One of the most interesting solutions to this problem is the use of water-forming NAD(P)H oxidases, NOX2 (herein termed NOX).…”

Section: Introductionmentioning

confidence: 99%

Bubble Column Enables Higher Reaction Rate for Deracemization of (R,S)‐1‐Phenylethanol with Coupled Alcohol Dehydrogenase/NADH Oxidase System

et al. 2019

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One of the major drawbacks for many biocatalysts is their poor stability under industrial process conditions. A particularly interesting example is the supply of oxygen to biooxidation reactions, catalyzed by oxidases, oxygenases or alcohol dehydrogenases coupled with NAD(P)H (reduced nicotinamide adenine dinucleotide phosphate) oxidases, which all require the continuous supply of molecular oxygen as an oxidant or electron acceptor. Commonly, oxygen is supplied to the bioreactor by air sparging. To ensure sufficient oxygen transfer from the gas to the liquid phase, stirring is essential to disperse the gas bubbles and create high gas-liquid interfacial area. Studies indicate that the presence of gas-liquid interface induces enzyme deactivation by protein unfolding which then readily aggregates and can subsequently precipitate. This contribution has examined the effects of stirring and the presence of gas-liquid interface on the kinetic stability of water-forming NAD(P)H oxidase (NOX) (EC1.6.3.2). These effects were studied separately and a bubble column apparatus was successfully employed to investigate the influence of gas-liquid interfaces on enzyme stability. Results showed that NOX deactivation increases in proportion to the gas-liquid interfacial area. While air enhances the rate of stability loss compared to nitrogen, stirring causes faster loss of activity in comparison to a bubble column. Finally, deracemization of 1phenylethanol, using a coupled alcohol dehydrogenase /NADH oxidase system (ADH/NOX), proceeded with a higher rate in the bubble column than in quiescent or in a stirred solution, although, inactivation was also accelerated in the bubble column over a quiescent solution.

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Recent advances in enzymatic oxidation of alcohols

Cited by 78 publications

References 72 publications

The Mechanism of Sugar C−H Bond Oxidation by a Flavoprotein Oxidase Occurs by a Hydride Transfer Before Proton Abstraction

The Mechanism of Sugar C−H Bond Oxidation by a Flavoprotein Oxidase Occurs by a Hydride Transfer Before Proton Abstraction

Broadening the Scope of Biocatalysis in Sustainable Organic Synthesis

Bubble Column Enables Higher Reaction Rate for Deracemization of (R,S)‐1‐Phenylethanol with Coupled Alcohol Dehydrogenase/NADH Oxidase System

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