Correction: Glycosylated cyclophellitol-derived activity-based probes and inhibitors for cellulases.

[This corrects the article DOI: 10.1039/D0CB00045K.].

Glycosylated cyclophellitol-derived activity-based probes and inhibitors for cellulases.

Cellulases and related β-1,4-glucanases are essential components of lignocellulose-degrading enzyme mixtures. The detection of β-1,4-glucanase activity typically relies on monitoring the breakdown of purified lignocellulose-derived substrates or synthetic chromogenic substrates, limiting the activities which can be detected and complicating the tracing of activity back to specific components within complex enzyme mixtures. As a tool for the rapid detection and identification of β-1,4-glucanases, a series of glycosylated cyclophellitol inhibitors mimicking β-1,4-glucan oligosaccharides have been synthesised.

Towards broad spectrum activity-based glycosidase probes: synthesis and evaluation of deoxygenated cyclophellitol aziridines.

Activity-based protein profiling has emerged as a powerful tool for visualizing glycosidases in complex biological samples. Several configurational cyclophellitol isomers have been shown to display high selectivity as probes for glycosidases processing substrates featuring the same configuration. Here, a set of deoxygenated cyclophellitols are presented which enable inter-class profiling of β-glucosidases and β-galactosidases.

Photo-crosslinking of clinically relevant kinases using H89-derived photo-affinity probes.

The profiling of kinases using established proteomics techniques is hampered by their non-covalent mode-of-action. One way to overcome this caveat is the use of probes featuring photo-labelling groups that can be activated by UV irradiation to generate a reactive species that will establish a covalent bond to the enzyme. In this study we have used the well-known kinase inhibitor H89 as a lead for the development of probes for the affinity-based profiling of clinically relevant kinases.

A Set of Activity-Based Probes to Visualize Human (Immuno)proteasome Activities.

Proteasomes are therapeutic targets for various cancers and autoimmune diseases. Constitutively expressed proteasomes have three active sites, β1c, β2c, and β5c. Lymphoid tissues also express the immunoproteasome subunits β1i, β2i, and β5i.

Synthesis and Evaluation of Hybrid Structures Composed of Two Glucosylceramide Synthase Inhibitors.

Glucosylceramide metabolism and the enzymes involved have attracted significant interest in medicinal chemistry, because aberrations in the levels of glycolipids that are derived from glucosylceramide are causative in a range of human diseases including lysosomal storage disorders, type 2 diabetes, and neurodegenerative diseases. Selective modulation of one of the glycoprocessing enzymes involved in glucosylceramide metabolism-glucosylceramide synthase (GCS), acid glucosylceramidase (GBA1), or neutral glucosylceramidase (GBA2)-is therefore an attractive research objective. In this study we took two established GCS inhibitors, one based on deoxynojirimycin and the other a ceramide analogue, and merged characteristic features to obtain hybrid compounds.

Direct and two-step bioorthogonal probes for Bruton's tyrosine kinase based on ibrutinib: a comparative study.

Ibrutinib is a covalent and irreversible inhibitor of Bruton's tyrosine kinase (BTK) and has been approved for the treatment of haematological malignancies, such as chronic lymphocytic leukaemia, mantle cell lymphoma and Waldenström's macroglobulinemia. The covalent and irreversible nature of its molecular mode of action allows identification and monitoring of its target in an activity-based protein profiling (ABPP) setting. Fluorescent and biotinylated ibrutinib derivatives have appeared in the literature in recent years to monitor BTK in vitro and in situ.

Development of an acid ceramidase activity-based probe.

Acid ceramidase is responsible for the ultimate step in the catabolism of (glyco)sphingolipids by hydrolysis of ceramide into sphingosine and free fatty acid. Deficiency in acid ceramidase is the molecular basis of Farber disease. Here we report the synthesis and characterization of an activity-based acid ceramidase probe.

A sensitive gel-based method combining distinct cyclophellitol-based probes for the identification of acid/base residues in human retaining β-glucosidases.

Retaining β-exoglucosidases operate by a mechanism in which the key amino acids driving the glycosidic bond hydrolysis act as catalytic acid/base and nucleophile. Recently we designed two distinct classes of fluorescent cyclophellitol-type activity-based probes (ABPs) that exploit this mechanism to covalently modify the nucleophile of retaining β-glucosidases. Whereas β-epoxide ABPs require a protonated acid/base for irreversible inhibition of retaining β-glucosidases, β-aziridine ABPs do not.

Exploring functional cyclophellitol analogues as human retaining beta-glucosidase inhibitors.

The natural product, cyclophellitol and its aziridine analogue are potent mechanism-based retaining β-glucosidase inhibitors. In this paper we explore the inhibitory potency of a number of cyclophellitol analogues against the three human retaining β-glucosidases, GBA, GBA2 and GBA3. We demonstrate that N-alkyl cyclophellitol aziridine is at least equally potent in inhibiting the enzymes evaluated as its N-acyl congener, whereas the N-sulfonyl analogue is a considerably weaker inhibitor.

Exploring dual electrophiles in peptide-based proteasome inhibitors: carbonyls and epoxides.

Peptide epoxyketones are potent and selective proteasome inhibitors. Selectivity is governed by the epoxyketone dual electrophilic warhead, which reacts with the N-terminal threonine 1,2-amino alcohol uniquely present in proteasome active sites. We studied a series of C-terminally modified oligopeptides featuring adjacent electrophiles based on the epoxyketone warhead.