Hippeastrum hybrid lectin (HHL) isolated from amaryllis bulbs. It consists of four subunits of identical size and has a molecular weight of 50,000. HHL has an isoelectric point between pH 4.7 and pH 5.1. It only binds alpha-mannose residues, (alpha-1,3) and (alpha-1,6) linked mannosyl units, as well as some yeast galactomannans. HHL has a blood group specificity for rabbit.

Study shows when treatment of the linear alpha-1,3-mannan with periodate, resulting in oxidation of the terminal, nonreducing mannosyl group, reactivity with HHL was not reduced. Oligosaccharides containing either 1,3- or 1,6-linked mannosyl units are good inhibitors of HHL-mannan precipitation system. Observations suggests that HHL reacts not only with terminal but also with internal D-mannosyl residues. Lectin appears to possess extended binding sites complementary to at least three 1,6-linked mannosyl units. Those containing alpha-1,3- or alpha-1,6-mannosyl residues were retarded on immobilized HHL agarose column.