NMR Analysis of Carbohydrate-Binding Interactions in Solution: An Approach Using Analysis of Saturation Transfer Difference NMR Spectroscopy

Abstract

One of the most commonly used ligand-based NMR methods for detecting ligand binding is saturation transfer difference (STD) nuclear magnetic resonance (NMR) spectroscopy. The STD NMR method is an invaluable technique for assessing carbohydrate–lectin interactions in solution, because STD NMR can be used to detect weak ligand binding (K _d ca. 10⁻³–10⁻⁸ M). STD NMR spectra identify the binding epitope of a carbohydrate ligand when bound to lectin. Further, the STD NMR method uses ¹H-detected NMR spectra of only the carbohydrate, and so only small quantities of non-labeled lectin are required. In this chapter, I describe a protocol for the STD NMR method, including the experimental procedures used to acquire, process, and analyze STD NMR data, using STD NMR studies for methyl-β-d-galactopyranoside (β-Me-Gal) binding to the C-terminal domain of an R-type lectin from earthworm (EW29Ch) as an example.