Simultaneous Fluorescent Labelling and Biotinylation of Oligosaccharides: A Versatile Approach to the Analysis of Oligosaccharide Structure and Function

Abstract

Oligosaccharides participate in a variety of important biological functions, including interactions with specific receptors (1–4). A prerequisite to the discovery and exploration of such interactions is the comprehensive structural analysis of homogeneous oligosaccharide species. The purification of oligosaccharides from complex mixtures requires diverse techniques, as well as sensitive and specific detection. One way to achieve sensitive detection is to attach a chromophore to the reducing sugar by reductive amination (5, 6) (see Chapters 7,11,15,18 in this volume for other examples of such techniques). Fluorescent chromophores (in contrast to light-absorbing chromophores) can often permit detection in the low picomole range for high-pressure liquid chromatography (HPLC) and polyacrylamide gel electrophoresis (PAGE) techniques, and in the femtomole range in capillary electrophoresis. Furthermore, hydrophobic or anionic properties of the chromophoric groups can be exploited to improve oligosaccharide fractionation by either electrophoresis or HPLC (5–8). Often several multidimensional chromatographic techniques, based on different physical properties, are required to adequately resolve complex mixtures. Several examples have been described of “two-dimensional mapping” with fluorescent pyridylamino (PA)-coupled oligosaccharides (5, 9). More recently, 2-aminobenzamide has been employed as an alternate fluorescent tag which gives both nonselective and highly efficient coupling to oligosaccharides (10).