In nature, carbohydrates form an important family of biomolecules, as simple or complex carbohydrates, either alone or covalently linked to proteins or lipids. Most of the earlier studies on carbohydrates focused on plant polysaccharides, such as cellulose, starch, pectins, and so on, largely because of their wide range of applications. More recently, the role of carbohydrates in biological events has been recognized, and glycobiology has emerged as a new and challenging research area at the interface of biology and chemistry. Of special interest are the carbohydrate-mediated recognition events that are important in biological phenomena, which give a pivotal role to the study of protein-carbohydrate interactions. Actually, the binding protein partners of carbohydrates encompass a wide variety of macromolecules involved in functions such as recognition, biosynthesis, modiˆcation, hydrolysis, and so on (Figure 4.1).