Iminosugar‐Cyclopeptoid Conjugates Raise Multivalent Effect in Glycosidase Inhibition at Unprecedented High Levels

Abstract

A series of cyclopeptoid-based iminosugar clusters has been evaluated to finely probe the ligand content-dependent increase in α-mannosidase inhibition. This study led to the largest binding enhancement ever reported for an enzyme inhibitor (up to 4700-fold on a valency-corrected basis), which represents a substantial advance over the multivalent glycosidase inhibitors previously reported. Electron microscopy imaging and analytical data support, for the best multivalent effects, the formation of a strong chelate complex in which two mannosidase molecules are cross-linked by one inhibitor.

Structural Basis of Outstanding Multivalent Effects in Jack Bean α‐Mannosidase Inhibition

“…[8a,b] These mammalian enzymes participate in the biosynthesis and catabolism of N-glycans in cells, [8b] and as such constitute targets for the treatment of cancers and lysosomal diseases. [5][6][7] These studies have led to an umber of competing hypotheses and binding models involving large aggregates,a dditional interactions with enzyme subsites,o rt he formation of discrete cross-linked complexes. [5][6][7] These studies have led to an umber of competing hypotheses and binding models involving large aggregates,a dditional interactions with enzyme subsites,o rt he formation of discrete cross-linked complexes.…”

“…[1] Catalytic hydrolysis of glycosidic linkages,t he most stable covalent single bonds within biopolymers,i safundamental process involved in key cellular events,i ncluding energy uptake and post-translational modifications of glycoproteins. [3][4][5][6][7] Although intensive efforts have been made to rationalize the inhibitory multivalent effect observed, how multimeric inhibitors and glycosidases interact at the atomic level remains unknown. [3][4][5][6][7] Although intensive efforts have been made to rationalize the inhibitory multivalent effect observed, how multimeric inhibitors and glycosidases interact at the atomic level remains unknown.…”

“…[9] In the absence of a3 Dc rystallographic structure for JBa-man, interactions with multivalent inhibitors have been studied by indirect methods,s uch as atomic force microscopy,dynamic light scattering,NMR spectroscopy,o rm ass spectrometry. [5][6][7] Herein we report the first high-resolution crystal structures of apo JBa-man and its complex with the 36valent cluster 1 [7] (Figure 1). [5][6][7] Herein we report the first high-resolution crystal structures of apo JBa-man and its complex with the 36valent cluster 1 [7] (Figure 1).…”

Understanding multivalent effects in glycosidase inhibition using C-glycoside click clusters as molecular probes

“…[1][2][3][4] First, because these enzymes which powerfully catalyse glycosidic cleavage in carbohydrates and glycoconjugates, do not exhibit the typical structural features required for multivalent design. Glycosidases indeed display generally a single, buried catalytic site 5 and bind to their monovalent substrates with high affinity and selectivity.…”

“…It is worth noting that systems that do not allow chelation mechanisms typically show moderate multivalent effects and require ligands with very high valency (>ca 100-150) to reach significant affinity enhancements. 10f Considering these points, how to explain that the multivalent effects observed in glycosidase inhibition with neoglycoclusters displaying up to 36 iminosugar ligands 2,3 rival those encountered for carbohydrate-lectin interactions? To answer to this fundamental question, the molecular basis of the rather counter-intuitive inhibitory multivalent effect has been explored independently by several groups using different strategies 3,11,12a,13,14 and complementary techniques including isothermal titration calorimetry, 12a mass spectrometry, 3 electron microscopy imaging 3 and atomic force microscopy.…”