Amaranthus hypochondriacus and A. tricolor lectins: isolation and characterization

Area of Science:

• Biochemistry
• Plant Science
• Molecular Biology

Background:

• Lectins are proteins with diverse biological functions, including carbohydrate binding.
• Amaranthus species are known sources of lectins with potential applications.

Purpose of the Study:

• To purify and characterize lectins from Amaranthus hypochondriacus Linn (AHL) and Amaranthus tricolor Linn (ATL).
• To investigate the biochemical properties and hemagglutination activity of these Amaranthus lectins.

Main Methods:

• Affinity purification using asialofetuin-linked amino-activated silica.
• PAGE, SDS-PAGE, gel exclusion chromatography (Biogel P-200, HPLC 300 SW), and ion-exchange chromatography.
• Isoelectric focusing to analyze protein heterogeneity.

Main Results:

• Purified AHL and ATL lectins showed specific inhibition by N-acetyl-D-galactosamine, fetuin, and asialofetuin.
• Both lectins exhibited hemagglutination activity against human and animal erythrocytes.
• Electrophoretic and chromatographic analyses indicated homogeneity, while isoelectric focusing revealed heterogeneity.
• AHL and ATL are dimeric glycoproteins with subunit molecular weights of 29,000 and 39,000, respectively, not linked by disulfide bonds.
• The lectins' agglutination activity is independent of divalent cations (Ca2+, Mn2+, Mg2+).

Conclusions:

• Asialofetuin-affinity chromatography is effective for purifying Amaranthus lectins.
• AHL and ATL lectins are distinct dimeric glycoproteins with conserved carbohydrate-binding specificities and hemagglutination properties.
• The characterization provides insights into the structure-function relationship of Amaranthus lectins.