Purification and Characterization of a Novel D-Galactose Binding Lectin from Seeds of Meizotropis buteiformis.

Plant lectins are carbohydrate-binding proteins that are ubiquitously found in almost all plant species and have different structures and functions depending on the sources. Purifying lectins from their plant sources and determining their sugar specificity become an important goal for evaluating their potential biomedical applications. Here, we report the affinity purification of a Dgalactose specific lectin from the seeds of Meizotropis buteiformis Voigt., and its physicochemical parameters, and LC-MS/MS (tandem mass spectrometry) analysis. Isolation and purification of this lectin were performed by simple successive steps of lectin extraction, ammonium sulphate fractionation, and affinity chromatography using lactose-linked Sepharose-4B chromatography column. The affinity-purified lectin has a native molecular weight of 75 kDa and is found to be a heterodimer (molecular weight of 36 and 38 kDa). The LC-MS/MS results suggested that the purified lectin had not been reported earlier. AIM: The main aim of the present study is to find out the novelty and characteristics of a lectin purified from the plant Meizotropis buteiformis. BACKGROUND: Lectins are proteins that possess the ability to specifically bind glycans of glycoconjugates. Plants are considered rich sources of lectins and the determination of sugar specificity of a purified plant lectin is an important aspect in order to evaluate its potential area of application. In the present study, a novel D-Galactose specific lectin is purified from Meizotropis buteiformis through affinity chromatography and examined for its various physical and biochemical characteristics. OBJECTIVE: The objective of the present study is to purify a novel lectin up to its homogeneity from the seeds of Meizotropis buteiformis and characterization of its various physical and biochemical properties. METHODS: The lectin was purified by simple successive steps of lectin extraction, ammonium sulphate fractionation, and affinity chromatography. Activity of the purified lectin was determined by hemagglutination assay. Some physicochemical parameters of the purified protein were also determined along with identification of protein by LC-MS/MS and the spectra analysis using Mascot sequence matching software (Matrix Science) with the NCBI database. RESULTS: From the current investigation, it was found that the purified lectin has a native molecular weight of 75 kDa. Among the various sugars and sugar derivatives tested, lactose and D-galactose were found to be potent inhibitors of its activity. Its optimum pH range was found to be from 6.5 to 7.5 and also it exhibited full activity at a temperature from 0ºC to 50ºC. The purified lectin does not show any effects on its activities for metal ions tested. The protein view report of the LC-MS/MS result analysis showed a 50% sequence similarity with that of the lectin beta-chain of the Butea monosperma. CONCLUSION: In the present study, a novel D-Galactose specific lectin is purified from Meizotropis buteiformis by affinity chromatography using Sepharose 4B. The purified lectin is found to be heterodimeric and metal ion independent. The LC-MS/MS results suggested that the purified lectin has not been reported earlier.

Purification and Characterization of a Novel Rhamnose/Fucose-Specific Lectin from the Hemolymph of Oak Tasar (Antheraea proylei J.) Silkworm.

BACKGROUND: Lectins are proteins or glycoproteins of non-immune origin which bind specifically but reversibly to carbohydrates or glycoconjugates. They play a crucial role in various biological processes including host defense mechanism, inflammation and metastasis. Therefore, there is an expanding scientific emphasis on purification and characterization of novel lectins possessing different useful biological properties. OBJECTIVE: The present investigation is concerned with purification and characterization of a novel lectin from the hemolymph of oak tasar (Antheraea proylei J.) silkworm. METHODS: The lectin was purified from the hemolymph by a procedure involving successive steps of hemocyte-free hemolymph preparation, ammonium sulfate (0-40%) fractionation and affinity chromatography on a column of Sephadex G-50 covalently coupled with L-rhamnose. It was then characterized by various physico-chemical methods including SDS-PAGE, gel filtration, hemagglutination assay, hemagglutination inhibition assay and tandem mass spectrometry (LCMS/ MS) coupled with Mascot sequence matching software (Matrix Science). RESULTS: The lectin was purified to electrophoretic homogeneity from the silkworm hemolymph and was found to be a monomeric protein with a native molecular weight of 39.5 kDa. It was specifically inhibited by L-rhamnose and D-fucose, the former being sixteen times more inhibitory than the latter. The hemagglutinating activity was further characterized by independency of metal ion, optimum at pH 7-7.5 and thermal stability with t1/2 of 60°C. Analysis with tandem mass spectrometry coupled with Mascot sequence matching software confirmed the purified lectin to be a protein not purified and characterized earlier. CONCLUSION: A novel rhamnose/fucose-specific lectin was purified to electrophoretic homogeneity from the hemolymph of oak tasar (Antheraea proylei J.) silkworm. The lectin was found to be a monomeric protein with a native molecular weight of 39.5 kDa. Its activity was found to be independent of metal ion, optimum at pH 7-7.5 and characterized by thermal stability with t1/2 of 60°C. Analysis with tandem mass spectrometry coupled with Mascot sequence matching software confirmed the purified lectin to be a protein not characterized earlier.

Biomedical Applications of Lectins from Traditional Chinese Medicine.

Lectins are proteins or glycoproteins of non-immune origin which have at least one noncatalytic domain that bind reversibly to specific mono or oligosaccharides. Traditional Chinese Medicine (TCM) involves a broad range of medicinal practices sharing common concepts which have been developed in China and are based on a tradition of more than thousands of years. Plant materials which are commonly used in TCM as a complementary or alternative for Western medical treatments contain a considerable number of important lectins. These lectins have been reported to have various applications and uses such as cancer treatment, glycoconjugate research, biomarker development, and others. Here, we summarize the available literature related to lectins from TCM and recent trends in their potential biomedical applications.