19F NMR studies of fluorinated sugars binding to the glucose and galactose receptor

Abstract

Publisher Summary Fluorodeoxy sugars have been utilized to examine enzyme specificities and mechanisms of glycogen phosphorylase and phosphoglucomutase, and measurement of the binding capacity of a series of fluorodeoxy sugars with individual substitutions for each hydroxyl provides insight into the role of each hydroxyl in the carbohydrate-protein complex. This chapter describes methods that illustrate how NMR can be used to investigate the role of each hydroxyl in the carbohydrate/protein complex and how to determine anomeric specificity in binding of sugars to large molecular weight proteins. 19 F NMR is a powerful technique due to several unique features of the fluorine nucleus, and this nucleus is a unique probe for environmental changes in proteins. Fluorinated sugars bound to receptor exhibit a downfield shift in the 19 F NMR spectrum; these shifts correspond to a deshielding of the fluorine nucleus upon sequestering of the sugar in the binding pocket of the receptor and can reflect desolvation and/or closer van der Waals interactions of the sugar upon binding. The chapter discusses the utility of 19 F NMR for characterizing the nature of carbohydrate/protein interactions, and the well defined spectra illustrate the beauty of the NMR methods to provide valuable information about exchange rates, anomeric preferences, and effect of temperature on binding events in these large protein systems.