Garlic (Allium sativum) lectins bind to high mannose oligosaccharide chains

Abstract

Two mannose-binding lectins, Allium sativum agglutinin (ASA) I (25 kDa) and ASAIII (48 kDa), from garlic bulbs have been purified by affinity chromatography followed by gel filtration. The subunit structures of these lectins are different, but they display similar sugar specificities. Both ASAI and ASAIII are made up of 12.5- and 11.5-kDa subunits. In addition, a complex (136 kDa) comprising a polypeptide chain of 54 ± 4 kDa and the subunits of ASAI and ASAIII elutes earlier than these lectins on gel filtration. The 54-kDa subunit is proven to be alliinase, which is known to form a complex with garlic lectins. Constituent subunits of ASAI and ASAIII exhibit the same sequence at their amino termini. ASAI and ASAIII recognize monosaccharides in mannosyl configuration. The potencies of the ligands for ASAs increase in the following order: mannobiose (Manα1-3Man) < mannotriose (Manα1-6Manα1-3Man) ≃ mannopentaose