IRMPD spectroscopy sheds new (InfraRed) light on the sulfate pattern of carbohydrates

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Heavily fluorinated carbohydrates as enzyme substrates: oxidation of tetrafluorinated galactose by galactose oxidase

Galactose oxidase (GOase) was shown to oxidise several C2/C3 fluorinated galactose analogues. Interestingly, the enzyme was able to distinguish between the 2,3-tetrafluorinated galactose and its epimeric glucose analogue, and this represents the first reported biotransformation of a heavily fluorinated suga

Enzymatic synthesis of N-acetyllactosamine from lactose enabled by recombinant β1,4-galactosyltransferases

Utilising a fast and sensitive screening method based on imidazolium-tagged probes, we report unprecedented reversible activity of bacterial β1,4-galactosyltransferases to catalyse the transgalactosylation from lactose to N-acetylglucosamine to form N-acetyllactosamine in the presence of UDP. The process is demonstrated by the preparative scale synthesis of pNP-β-LacNAc from lactose using β1,4-galactosyltransferase NmLgtB-B as the only biocatalyst

Application of bio-based solvents for biocatalysed synthesis of amides with Pseudomonas stutzeri lipase (PSL)

Bio-based solvents were investigated for the biocatalysed amidation reactions of various ester-amine combinations by Pseudomonas stutzeri lipase (PSL). Reactions were undertaken in a range of green and potentially bio-based solvents including terpinolene, p-cymene, limonene, 2-methyl THF, ɣ-valerolactone, propylene carbonate, dimethyl isosorbide, glycerol triacetate and water. Solvent screenings demonstrated the importance and potential of using non-polar bio-based solvents for favouring aminolysis over hydrolysis; whilst substrate screenings highlighted the unfavourable impact of reactants bearing bulky para- or 4-substituents. Renewable terpene-based solvents (terpinolene, p-cymene, D-limonene) were demonstrated to be suitable bio-based media for PSL amidation reactions. Such solvents could provide a greener and more sustainable alternative to traditional petrochemical derived non-polar solvents. Importantly, once the enzyme (either PSL or CALB) binds with a bulky para-substituted substrate, only small reagents are able to access the active site. This therefore limits the possibility for aminolysis to take place, thereby promoting the hydrolysis. This mechanism of binding supports the widely accepted 'Ping Pong - Bi Bi' mechanism used to describe enzyme kinetics. The work highlights the need to further investigate enzyme activity in relation to para- or 4-substituted substrates. A priority in PSL chemistry remains a methodology to tackle the competing hydrolysis reaction

Enzymatic Late‐Stage Modifications: Better Late Than Never

From Wiley via Jisc Publications RouterHistory: received 2020-11-08, rev-recd 2021-01-15, pub-electronic 2021-03-08, pub-print 2021-07-26Article version: VoRPublication status: PublishedFunder: EPSRC; Grant(s): EP/S005226/1Funder: BBSRC; Grant(s): EP/S005226/1Funder: AstraZeneca plc; Id: http://dx.doi.org/10.13039/100004325; Grant(s): EP/S005226/1Funder: European Research Council; Id: http://dx.doi.org/10.13039/100010663; Grant(s): 742987-BIO-H-BORROW-ERC-2016-ADG, 788231-ProgrES-ERC-2017-ADGAbstract: Enzyme catalysis is gaining increasing importance in synthetic chemistry. Nowadays, the growing number of biocatalysts accessible by means of bioinformatics and enzyme engineering opens up an immense variety of selective reactions. Biocatalysis especially provides excellent opportunities for late‐stage modification often superior to conventional de novo synthesis. Enzymes have proven to be useful for direct introduction of functional groups into complex scaffolds, as well as for rapid diversification of compound libraries. Particularly important and highly topical are enzyme‐catalysed oxyfunctionalisations, halogenations, methylations, reductions, and amide bond formations due to the high prevalence of these motifs in pharmaceuticals. This Review gives an overview of the strengths and limitations of enzymatic late‐stage modifications using native and engineered enzymes in synthesis while focusing on important examples in drug development

Lipase-catalysed acylation of starch and determination of the degree of substitution by methanolysis and GC

Background: Natural polysaccharides such as starch are becoming increasingly interesting as renewable starting materials for the synthesis of biodegradable polymers using chemical or enzymatic methods. Given the complexity of polysaccharides, the analysis of reaction products is challenging. Results: Esterification of starch with fatty acids has traditionally been monitored by saponification and back-titration, but in our experience this method is unreliable. Here we report a novel GC-based method for the fast and reliable quantitative determination of esterification. The method was used to monitor the enzymatic esterification of different starches with decanoic acid, using lipase from Thermomyces lanuginosus. The reaction showed a pronounced optimal water content of 1.25 mL per g starch, where a degree of substitution (DS) of 0.018 was obtained. Incomplete gelatinization probably accounts for lower conversion with less water. Conclusions: Lipase-catalysed esterification of starch is feasible in aqueous gel systems, but attention to analytical methods is important to obtain correct DS values

Enzymkatalysierte späte Modifizierungen: Besser spät als nie

From Wiley via Jisc Publications RouterHistory: received 2020-11-08, rev-recd 2021-01-15, pub-electronic 2021-03-08, pub-print 2021-07-26Article version: VoRPublication status: PublishedFunder: EPSRC; Grant(s): EP/S005226/1Funder: BBSRC; Grant(s): EP/S005226/1Funder: AstraZeneca plc; Id: http://dx.doi.org/10.13039/100004325; Grant(s): EP/S005226/1Funder: European Research Council; Id: http://dx.doi.org/10.13039/100010663; Grant(s): 742987-BIO-H-BORROW-ERC-2016-ADG, 788231-ProgrES-ERC-2017-AD