A Chemoenzymatic Approach for the Synthesis of Unnatural Disaccharides Containing D‐Galacto‐ or D‐Fucofuranosides

Abstract

Unusual diglycosides composed of D-hexofuranosyl entities were prepared by a chemoenzymatic route using the α-L-arabinofuranosidase, AbfD3. The required, unprotected monosaccharidic donors were first prepared according to multistep syntheses. Since one goal of this study was the investigation of donor -1 subsite in the active site of the enzyme, we focused on D-fucofuranosyl and 6-deoxy-6-fluoro-Dgalactofuranosyl derivatives which present stereochemical similarities with L-arabinose series, but also structural varia-

Functional roles of H98 and W99 and β2α2 loop dynamics in the α‐l‐arabinofuranosidase from Thermobacillus xylanilyticus

“…Moreover, the experimental values for K d obtained in this work were similar (0.16 ± 0.06 and 0.32 ± 0.09 mm) and consistent with both the values of K M (0.72 ± 0.04 mm) and the previously measured K d value (0.21 ± 0.02 mm) for the binding of XA 3 XX [6]. Nevertheless, it is noteworthy that the STD intensity attributed to the H-5 was weaker, suggesting either that this proton is less involved in substrate binding or that the hydroxymethyl moiety remains mobile in the bound state (internal motions of substrates being a known cause of reduction of STD effects) or simply that pNP-a-l-Araf is not bound in exactly the same way as XA tent with the observation that the b-d-fucofuranosyl moiety of pNP-b-d-fucofuranoside can be accommodated in subsite )1 without inducing drastic changes in K M [28]. However, the failure of STD-NMR and ITC analysis to reveal any STD effects or binding when pNP-b-d-Galf was employed as the substrate further confirms that the presence of the extra hydroxymethyl group (C-6) is extremely detrimental for sugar binding in subsite )1.…”

Synthesis of galactofuranose-containing disaccharides using thioimidoyl-type donors

“…52 To explain the apparent inhibition of the Williamson etherification by the 1,2-cis-anomer, we assumed that the standard tritylation reagent was not reactive enough, and more importantly, that the nucleophilic base DMAP could engage in competitive reactions, that is, (i) nucleophilic activation of TrCl and (ii) possible deprotonation of the more acidic and more hindered 2-hydroxyl function in the 1,2-cis galactoside 14a. Such a property, which proved to be of particular interest in selective 2-O-protection, 53 was suspected to be a factor that disfavoured the protection of the primary hydroxyl. On this basis, the introduction of the trityl group was first attempted starting from the pure 14b and the more reactive p-methoxyphenyldiphenyl chloride (MMTrCl).…”

Galactofuranosidase from JHA 19 Streptomyces sp.: subcloning and biochemical characterization

“…Therefore, reported chemo-enzymatic procedures in literature all used cloned α-L-arabinofuranosidases as biocatalytic tools, based on the structure similarity between pNP β-D-Galf 1 and its analogue pNP α-L-Araf 2 (Fig 1.). [12][13][14] However,…”