MANNOSE SPECIFIC LECTINS FROM EDIBLE GARLIC (ALLIUM SATIVUM)

Anita Gupta
Department of Biotechnology, University Institute of Engineering and Technology,
Panjab University, Chandigarh - 160 014

Abstract

Lectins constitute a heterogeneous group of carbohydrate binding proteins of non-immune origin, which agglutinate cells and/or precipitate glycoconjugates without affecting their covalent linkages. Mannose specific lectins have been reported from monocot species, namely Narcissus pseudonacissus, leucojum aestivum M, Leucojum vernum N, and Alliaceae. The mannose specific lectins from Alliaceae strongly resemble Amaryllidaceae lectins. Lectins specific for D-mannose differ from each other in their interactions with mono-oligosaccharides. This property enables them to distinguish D-mannose from D-glucose and thereby make them quite useful in biomedical research. The cDNA clones for two different lectins/agglutinins from garlic bulbs (Allium sativum), Allium sativum agglutinin-I (ASA-I) and ASA-II have been characterized. While the ASA-I, is a heterodimer composed of two different subunits of 11.5 kDa and 12.5 kDa, the ASA-II is a homodimer of two identical 12-kDa subunits. The use of an asialofetuin-silica affinity column has led to isolate agglutinin of 110 kDa besides lectins of 25 kDa. The ASA110 is a glycoprotein of two identical subunits of 47 kDa. In addition, a complex of 136 kDa comprising a polypeptide chain of 54 +/- 4 kDa and the subunits of ASA-I and ASA-III elutes earlier than these lectins on gel filtration. The physicochemical characterization, biological action, and nutritional toxicity of Allium sativum agglutinins have been reviewed.

Key words: Lectins; Garlic lectins; Allium sativum, Agglutinins, Mannose binding lectins.