Chapter 6 - Glycan-Binding Proteins and Glycan Microarrays

Abstract

This chapter provides an introduction to glycan-binding proteins (GBPs) and glycan microarrays. GBPs like plant lectins and anti-carbohydrate antibodies are important tools for detecting specific oligosaccharide (glycan) structures. Methods for measuring the interactions of GBPs with glycans are developed as a way of defining the specificity of the protein–carbohydrate interaction. The most widely used method to define glycan-binding specificity of GBPs is to inhibit the precipitation of a glycoprotein or agglutination of a particular cell type with available structurally defined glycans. The inhibition of precipitin formation, measured by quantifying precipitated protein or visible agglutination with known glycan structures, provides information about the relative binding affinity and overall specificity. This is a labor-intensive process used to monitor many agglutination reactions. The major limitations include the lack of structurally defined complex glycans that could be introduced into the inhibition analyses and the vast amounts of materials needed. This limitation is overcome by the development of solid-phase binding arrays, including printed glycan microarrays, which permit the rapid analysis of potentially hundreds of defined glycans in a single analysis. Glycan microarrays afford an unprecedented opportunity to explore a wide range of glycan recognition by GBPs, cells, and even organisms. Though still relatively limited in complexity and diversity of glycans, the microarrays have made profound impacts on a number of fields of study, including immunology, development, cancer, and infectious diseases.