Polymeric Iminosugars Improve the Activity of Carbohydrate- Processing Enzymes Yoan Brissonnet, † Simon Ladeve ̀ ze, ‡ David Teze ́ , † Emeline Fabre, § David Deniaud, † Franck Daligault, ⊥ Charles Tellier, ⊥ Sergej S ̌ esta ́ k, ∥ Magali Remaud-Simeon, ‡ Gabrielle Potocki-Veronese, ‡ and Se ́ bastien G. Gouin* ,† † LUNAM Universite ́ , CEISAM, Chimie Et Interdisciplinarite ́ , Synthè se, Analyse, Mode ́ lisation, UMR CNRS 6230, UFR des Sciences et des Techniques, 2, rue de la Houssinie ̀ re, BP 92208, 44322 Nantes Cedex 3, France ‡ Laboratoire d’Ingé nierie des Systè mes Biologiques et des Proce ́ de ́ s, Institut National des Sciences Applique ́ es, CNRS UMR5504, Institut National de Recherche Agronomique, UMR792, 135 Ave. de Rangueil, 31077 Toulouse, France § Universite ́ Lille 1, Unite ́ de Glycobiologie Structurale et Fonctionnelle, UMR 8576, 59650 Villeneuve d’Ascq, France ⊥ UFIP, UMR CNRS 6286, Faculte ́ des Sciences et Techniques, Universite ́ de Nantes, 2 rue de la Houssinie ̀ re, F-44322 Nantes, France ∥ Institute of Chemistry, Center for Glycomics, Slovak Academy of Sciences, Dú bravska cesta 9, 845 38 Bratislava, Slovakia * S Supporting Information ABSTRACT: Multivalent iminosugars have recently emerged as powerful tools to inhibit the activities of specific glycosidases. In this work, biocompatible dextrans were coated with iminosugars to form linear and ramified polymers with unprecedently high valencies (from 20 to 900) to probe the evolution of the multivalent inhibition as a function of ligand valency. This study led to the discovery that polyvalent iminosugars can also significantly enhance, not only inhibit, the enzymatic activity of specific glycoside-hydrolase, as observed on two galactosidases, a fucosidase, and a bacterial mannoside phosphorylase for which an impressive 70-fold activation was even reached. The concept of glycosidase activation is largely unexplored, with a unique recent example of small-molecules activators of a bacterial O-GlcNAc hydrolase. The possibility of using these polymers as “artificial enzyme effectors” may therefore open up new perspectives in therapeutics and biocatalysis. ■ INTRODUCTION Multivalency is a well-established and powerful approach to develop strong and selective inhibitors of carbohydrate-binding proteins called lectins. 1−3 The so-called “glycoclusters”, in which ligands are displayed in multiple copies on a synthetic core, mimic the glycocalyx displayed at the surface of cells and can lead to strong affinity enhancements compared to monovalent references. The simplicity and efficiency of the concept has led many groups to choose the multivalent way rather than improving the potency of a monovalent lead in a “lock and key” approach. Until recently, the multivalent approach has been most successful with lectins, with only a few studies reported on carbohydrate-processing proteins. A striking example in the field was the development of multi- and polyvalent inhibitors of influenza neuraminidase, which showed outstanding ability to inhibit influenza virus replication in vivo. 4,5 To estimate the potential of the multivalent approach in glycosidase inhibition, we previously designed a set of mono-, di-, and trivalent inhibitors of the deoxynojirimycin (DNJ) iminosugar, a broad specificity glycosidase inhibitor. 6 The inhibitory activity of these compounds measured on nine glycosidases demonstrated that the multivalent strategy cannot be considered a general mode of inhibition of these enzymes as it is with lectins. However, a small but significant multivalent effect was detected for the first time on Jack bean α-mannosidase (JbMan). Much lower inhibitory activities and higher multivalent effects were then observed on the same enzyme with DNJ compounds of higher valencies. 7,8 Interestingly, multivalent effects were also seen on therapeutically relevant carbohydrate-processing enzymes in- cluding (i) β-glucocerebrosidase for which the deficiency in hydrolyzing glucosylceramide can lead to Gaucher disease, 9 the most common form of lysosomal storage disorders, (ii) the bacterial heptosyl-transferase WaaC incorporating heptosyl subunits in the outer membrane of Gram-negative bacteria, 10 (iii) human liver glycogen phosphorylase, a target for the treatment of noninsulin dependent diabetes mellitus, 11 and (iv) ManIIb as a representative of Golgi α-mannosidase II, a potential target of anticancer therapy. 12 Multivalent iminosu- gars were also shown to be able to correct the cell-deficiency of Received: February 6, 2015 Revised: March 3, 2015 Published: March 5, 2015 Article pubs.acs.org/bc © 2015 American Chemical Society 766 DOI: 10.1021/acs.bioconjchem.5b00081 Bioconjugate Chem. 2015, 26, 766−772