Substrate recognition by sugar chain-related enzymes: Recognition of a large area of substrates and its strictness and tolerance

Abstract

Analysis of the substrate specificity of some sugar chain-related enzymes using homogeneous sugar chains (mainly fluorescently labeled sugar chains) can reveal the in vivo substrate of the enzyme. Such analyses have shown that these enzymes have the ability to recognize not only the sites of hydrolysis or glycosyl transfer but also other regions far apart from them. They can recognize a region consisting of pentasaccharides, hexasaccharides and, in some cases, decasaccharides or larger saccharides. The enzymes recognize part of the substrate strictly, and another part of it tolerantly. These analyses have also identified pairs of enzymes with substrate specificities that are complementary to each other. Here we describe some sugar chain-related enzymes with these properties. The biological significance of the recognition of a large substrate area and its strictness and tolerance will be discussed. ©2005 FCCA (Forum: Carbohydrates Coming of Age).