Are there any chitin-specific lectins?
A number of chitin-specific lectins have been described as a special class of chitin binding proteins. Most prominently, these are Wheat Germ Agglutinin (WGA) from wheat seeds (but also present in wheat leaves) and hevein from the latex tree Hevea brasiliensis. There is good evidence that WGA requires three consecutive GlcNAc residues for binding so that it is rather specific for chitin, but also binds to chitosans with high degree of acetylation. WGA tagged with different fluorescent markers such as FITC or Texas Red are commercially available and are being used for the cytochemical detection of chitin. Fusing chitin binding modules or (possibly inactivated) chitinases with fluorescent proteins such as GFP or YFP yields artificial chitin-specific 'lectins' which can be used for the same purposes. However, the distinction between chitin and chitosan requires double staining using chitin- and chitosan-specific probes.