Böcker av Rabia Hamid

Lectins are proteins or glycoproteins of non immune origin which have a wide distribution in animals, plants, and microorganisms. Their medicinal role extends from simple antimicrobial action to anti- tumour properties.In view of the advancement in understanding the potential medicinal role of the plant lectins, a lectin from the leaves of Prunella vulgaris was isolated, purified, partially characterized and its antimicrobial activity evaluated. The lectin is specific for galactose and N-acetyl-galactosamine The molecular weight of the lectin as determined by SDS-PAGE was 32500 Da and that estimated from Sephadex G-100 gel filtration column was 65000 Da indicating that the purified lectin is a homodimer. The purified lectin also shows a significant antimicrobial activity against the infectious agents of some common diseases such as Salmonella typhi, Klebseilla pnuemonea and Escherhia coli.

Plant lectins are a heterogeneous group of proteins or glycoproteins that share in common their ability to recognize and bind specific sugar residues. At present hundreds of plant lectins have been isolated and characterized with respect to their molecular structures and carbohydrate-binding specificities. Since the unique biological properties of lectins can be exploited in the investigation of numerous biochemical and cellular phenomena, intense efforts are being made in many labs to isolate lectins with unique and unusual sugar-binding specificities. The study deals with the purification and partial characterization of a lectin from Crotalaria pallida belonging to Leguminoseae. Conformational changes and changes in biological properties by chemical modification of the lectin are also a part of the study. The lectin is a monomeric galactose and blood group A specific glycoprotein with about 4% carbohydrate and a molecular weight of 43 kDa. The activity yield of the lectin was about 4.6% with nearly three fold purification. Conformational changes were investigated by gel filtration, viscometery and UV absorption spectroscopy.