NMR analysis of carbohydrate-binding interactions in solution: an approach using analysis of saturation transfer...

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 (Kd 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.