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Updated: Jul 3, 2026

Disentangling Glycan-Protein Interactions: Nuclear Magnetic Resonance (NMR) to the Rescue
Published on: May 17, 2024
Glycosidase inhibition by macrolide antibiotics elucidated by STD-NMR spectroscopy
Ali Sadeghi-Khomami1, Michael D Lumsden, David L Jakeman
1College of Pharmacy, Dalhousie University, Halifax, NS, B3H 1E9, Canada.
Abstract:
A glycosynthase approach was attempted to glycodiversify macrolide antibiotics, using DesR, a family-3 retaining beta-glucosidase involved in the self-resistance mechanism of methymycin production. STD-NMR was used to probe enzyme-substrate interactions. Analysis of competitive STD-NMR experiments between erythromycin A and a chromogenic substrate (pNP-beta-d-glucose) with the hydrolytically inactive nucleophile mutants led us to discover a family of unprecedented glycosidase inhibitors. Analysis of kinetic data with wild-type DesR determined that erythromycin is a competitive inhibitor of the glucosidase (IC50 = 2.8 +/- 0.3 microM and Ki = 2 +/- 0.2 microM) with respect to the hydrolysis of pNP-beta-d-glucose. Comparable inhibitory data was obtained for clarithromycin; however, the inhibitory effect of azithromycin was weak and no significant inhibition was observed with methymycin or d-desosamine. This report documents significant inhibition of glycosidases by macrolide antibiotics and provides insight into the design of novel glycosidase inhibitors based on the macrolactone ring of macrolide antibiotics.
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