Synthesis of aryl 3-O-β-cellobiosyl-β-d-glucopyranosides for reactivity studies of 1,3-1,4-β-glucanases

Planas, Antoni; Abel, Mireia; Millet, Óscar; Palasi, Josep; Pallarés, Cristina; Viladot, J.‐L.

doi:10.1016/s0008-6215(98)00175-x

Cited by 30 publications

(31 citation statements)

References 31 publications

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“…There are several possible scenarios with the Hammett plots for chemical glycosylations: 1) linear Hammett relationship for a wide range of leaving group σ p values, which will indicate that the glycosylation mechanism remains the same for all substituents; 2) bent Hammett relationship consisted of linear correlations with different slopes suggesting a change in mechanism. Such phenomena have been observed previously with several glycosidases,22, 28, 29 which resulted from rate limiting step change with different substituents; 3) Hammett relationship with poor linear correlations and badly scattered points implying factors other than substituent electronic effects influencing the reaction. Herein, we report the quantification of anomeric reactivities of three donor series 1a-1e , 2a-2e and 3a-3e .…”

Section: Introductionsupporting

confidence: 71%

Thio-arylglycosides with various aglyconpara-substituents: a probe for studying chemical glycosylation reactions

Huang

et al. 2009

Org. Biomol. Chem.

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Summary Three series of thioglycosyl donors differing only in their respective aglycon substituents within each series have been prepared as representatives of typical glycosyl donors. The relative anomeric reactivities of these donors were quantified under competitive glycosylation conditions with various reaction time, promoters, solvents and acceptors. Over three orders of magnitude reactivity difference were generated by simple transformation of the para-substituent on the aglycon with methanol as the acceptor, while chemoselectivities became lower with carbohydrate acceptors. Excellent linear correlations were attained between relative reactivity values of donors and σp values of the substituents in the Hammett plots. This indicates that the glycosylation mechanism remains the same over a wide range of reactivities and glycosylation conditions. The negative slopes of the Hammett plots suggested that electron donating substituents expedite the reactions and the magnitudes of slopes can be rationalized by neighboring group participation as well as electronic properties of the glycon protective groups. Within the same series of donors, less nucleophilic acceptors gave smaller slopes in their Hammett plots. This is consistent with the notion that acceptor nucleophilic attack onto the reactive intermediate is part of the rate limiting step of the glycosylation reaction. Excellent linear Hammett correlations were obtained between relative reactivity values of three series of donors differing only in their aglycon substituents and σp values of the substituents.

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Section: Introductionsupporting

confidence: 71%

Thio-arylglycosides with various aglyconpara-substituents: a probe for studying chemical glycosylation reactions

Huang

et al. 2009

Org. Biomol. Chem.

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“…4-Methylumbelliferone and 2,4-dinitrophenol were purchased from Fluka, and they were recrystallized from glacial acetic acid (Sigma Chemical Co.). The substrates 2,4dinitrophenyl 3-O-β-cellobiosyl-β--glucopyranoside (G4G3G-2,4DNP) [34] and 4-methylumbelliferyl 3-O-β-cellobiosyl-β-glucopyranoside (G4G3G-MU) [35,36] were synthesized as described previously. All buffers and solutions for kinetic experiments and reaction monitoring were filtered (0.45 µm) prior to use.…”

Section: Enzymes and Reagentsmentioning

confidence: 99%

“…Reactions were initiated by addition of substrate to a preincubated mixture of buffer, calcium chloride, enzyme and exogenous nucleophile, and the absorbance changes at 365 nm for G4G3G-MU (release of 4-methylumbelliferone ; ∆ε $'& l 5136 M −" :cm −" ) or 425 nm for G4G3G-2,4DNP (release of 2,4-dinitrophenol ; ∆ε %#& l 6134 M −" :cm −" ) were monitored. Values of ∆ε were carefully determined under the assay conditions as reported previously [31,34].…”

Section: Enzyme Kinetics With G4g3g-24dnp and G4g3g-mumentioning

confidence: 99%

Long-lived glycosyl-enzyme intermediate mimic produced by formate re-activation of a mutant endoglucanase lacking its catalytic nucleophile

Viladot¹,

Canals²,

Batllori³

et al. 2001

Biochem. J.

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The mutant E134A 1,3-1,4-beta-glucanase from Bacillus licheniformis, in which the catalytic nucleophilic residue has been removed by mutation to alanine, has its hydrolytic activity rescued by exogenous formate in a concentration-dependent manner. A long-lived alpha-glycosyl formate is detected and identified by (1)H-NMR and matrix-assisted laser desorption ionization-time-of-flight-MS. The intermediate is kinetically competent, since it is, at least partially, enzymically hydrolysed, and able to act as a glycosyl donor in transglycosylation reactions. This transient compound represents a true covalent glycosyl-enzyme intermediate mimic of the proposed covalent intermediate in the reaction mechanism of retaining glycosidases.

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“…The maltoheptaose backbone of the two novel colorimetric and fluorometric substrates III and IV was obtained via the controlled acetolysis of β ‐cylodextrin as described by Farkas et al The semi‐purified per‐ O ‐acetylated maltoheptaose was subsequently functionalised following the protocol previously developed by Planas et al to produce precursors of III and IV lacking the benzylidene acetal protecting group. This was introduced on the hydroxyl groups at positions 4 and 6 of the glucosyl residue at the non‐reducing end via a regioselective reaction in the last synthetic step to afford the desired substrates III and IV respectively.…”

Section: Methodsmentioning

confidence: 99%

Novel assay procedures for the measurement of α‐amylase in weather‐damaged wheat

Cornaggia¹,

Ivory²,

Mangan³

et al. 2015

J Sci Food Agric

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Synthesis of aryl 3-O-β-cellobiosyl-β-d-glucopyranosides for reactivity studies of 1,3-1,4-β-glucanases

Cited by 30 publications

References 31 publications

Thio-arylglycosides with various aglyconpara-substituents: a probe for studying chemical glycosylation reactions

Thio-arylglycosides with various aglyconpara-substituents: a probe for studying chemical glycosylation reactions

Long-lived glycosyl-enzyme intermediate mimic produced by formate re-activation of a mutant endoglucanase lacking its catalytic nucleophile

Novel assay procedures for the measurement of α‐amylase in weather‐damaged wheat

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