Isolation and Characterization of Lectins from Dolichos lablab and Lagenaria siceraria

By : Prachi Nikam, Kanchan Chitnis

Page No: 151-156

Abstract:
Lectins are proteins found in plants and different organisms. They possess the ability to bind to specific carbohydrate and can agglutinate erythrocytes. In the present study, two Indian varieties of plants namely, Field Beans (Dolichos lablab) and Bottle Gourd (Lagenaria siceraria) were used to extract and characterize lectins for their haemagglutination activity against the human ABO blood group antigens. Boiled and unboiled seeds and pulp were used. Crude extracts were prepared using 0.15M NaCl solution and were estimated for proteins by Biuret method. Salting out fractions were obtained using Ammonium sulphate and proteins from these fractions were estimated by Folin Lowry method. Field beans had higher protein content (4.76mg/ml) than Bottle Gourd (1.05 mg/ml) and there was a decrease in protein content after boiling(2.12 mg/ml, and 0.58 mg/ml respectively). The crude extract and fractions were assayed for qualitative and quantitative hemagglutination activity and sugar specificity. Field Beans extract of unboiled seeds showed agglutination with human blood group A and B and showed a very high intensity with Hemagglutination Units (HU) of 1024. Field Beans extract showed agglutination with blood group A even after boiling, although the intensity was lesser than unboiled extract. Bottle Gourd extracts did not show any agglutination activity. Positive haemagglutination for Blood Group A and B was observed exclusively in Dolichos lablab fraction: 0-25%. The other fractions did not show any haemagglutination activity indicating that lectin was extracted in the 0-25% fraction. This fraction was electrophoresed by Native PAGE. A single band of approximately 66.5kDa was observed on the gel. Lectins of Dolichos lablab were found to bespecific for sugars- Glucose, Galactose and Lactose. From this study, it was concluded that boiling decreased the lectin activity but did not completely alleviate it. This is contrary to the belief that boiling leads to complete removal of lectin activity. Agglutination activity of Dolichos lablab lectin can be used in blood typing and also in differentiation of normal and aberrant cells. Lectins can help in early detection of changes in cell topology, especially in cancer. The lectin from Dolichos lablab has shown to be very potent, with very high agglutination titreunits. Thus, it shows great promise in detecting very subtle changes in glyco-topology of aberrant cells.

Authors:
Prachi Nikam : Post Graduate Student of Department of Life Science, Ramnarain Ruia Autonomous College, L.N.Road, Matunga East, Mumbai, India, 400019
Kanchan Chitnis :Assistant Professor, Department of Life Science, Ramnarain Ruia Autonomous College, L.N. Road, Matunga East, Mumbai, India, 400019.

DOI: https://doi.org/10.32381/JPSR.2020.36.1-2.20