Cell surface carbohydrates play important roles in many biological and pathological processes. One of their modes of activity is through binding interactions with lectins. However, many of carbohydrate–lectin interactions are thought to remain unknown due to their low affinity, overlapping specificity and the lack of general tools to detect and isolate specific lectins. Photoaffinity labeling has emerged as a promising approach to investigate often elusive carbohydrate–protein interactions. This minireview aims to illustrate challenges associated in identifying carbohydrate–lectin interactions and to briefly present past developments in the design of carbohydrate photoaffinity probes.
A β-1,3-D-glucan called Schizophyllan (SPG) can form a novel complex with homo oligodeoxynucleotides (ODNs) via the combination of hydrogen bonding and hydrophobic interactions. Dectin-1 is a major receptor involved in the recognition of β-1,3-D-glucans and expressed on antigen presenting cells (APCs) including macrophages, dendritic cells, monocytes, neutrophils, and a subset of T cells. Therefore, the SPG/ODN complex can be used as APCs cell-specific delivery of antisense ODNs (AS-ODNs) or unmethylated CpG sequences (CpG-ODNs). In fact, AS-ODN/SPG complex protected mice from LPS-induced hepatitis and CpG-ODN/SPG complex induced high antibody titers when it was administered to cynomolgus monkeys as adjutant of influenza vaccine. These results indicate that SPG can be an excellent drug delivery system carrier targeting APCs.