Synthesis of broad-specificity activity-based probes for exo-β-mannosidases

Abstract

Exo--mannosidases are a broad class of stereochemically retaining hydrolases that are essential for the breakdown of complex carbohydrate substrates found in all kingdoms of life. Yet the detection of exo--mannosidases...

The development of a broad-spectrum retaining β-exo-galactosidase activity-based probe

“…MANBA is responsible for the cleavage of the core Man-β-1,4-GlcNAc linkage during lysosomal turnover of N -glycoproteins. 43 We previously found that MANBA also reacts with retaining β-glucosidase targeting probes 44 and it appears that the MANBA active site is flexible and can accommodate, besides mannopyranose-configured ligands, also glucopyranose and galactopyranose ones. GBA1, whose physiological role is to degrade glucosylceramidase and thus is the penultimate enzyme in the lysosomal turnover of glycosphingolipids, has previously been shown to be cross-reactive towards β-galactopyranose-configured ligands – substrates, competitive inhibitors and mechanism-based irreversible inhibitors.…”

“…The solvents were evaporated and 1 H NMR analysis showed the presence of circa 10 mol% of tetrazine 4 co-eluting with the target compound on HPLC. The crude material was dissolved in MeOH (1 mL) and treated with 0.40 mL of a methanolic solution (10 mg mL −1 ) of (bicyclo[2.2.1]hept-5-en-2-yl)methyl tert -butyldimethylsilyl ether 44 to remove unreacted tetrazine before HPLC purification of aziridine probe 5 . HPLC purification afforded two fractions, each containing two isomers, of probe 5 in a total yield of 39%.…”

Site-Selective Modification of (Oligo)Saccharides

“…These functional groups are a challenge to combine with benzyl, CBz, and Boc protecting groups due to the conditions of the removal of the latter. 26 Introducing these reactive groups in unprotected sugars can be a solution to this problem. The introduction of an azide functionality at a secondary hydroxy group in unprotected sugars via late-stage modification has rarely been reported, although the known sequence “site-selective oxidation-reductive amination” could be coupled to azide transfer.…”

“…This can be a serious issue; frequently used reactive groups used in carbohydrate chemical biology are epoxides, (acyl)­aziridines, azirines, alkynes, and azides (Scheme A). These functional groups are a challenge to combine with benzyl, CBz, and Boc protecting groups due to the conditions of the removal of the latter . Introducing these reactive groups in unprotected sugars can be a solution to this problem.…”

Rational Tuning of the Reactivity of Three‐Membered Heterocycle Ring Openings via SN2 Reactions

“…The specific reaction shown corresponds to the labelling of a retaining glycosidase (PDB ID: 7OMS) by a mannose‐configured epi‐cyclophellitol‐based aziridine. The exact mechanism naturally depends on many factors, for example, type and nature of the enzyme, the pH and the specific architecture of the inhibitor [3c] . b) Computationally analysed model ring‐opening reactions by nucleophile AcO − with the lower‐energy α‐attack (chair‐like transition state); [4] c) Library of studied substrates ( 1 – 16 ).…”