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

Abstract

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. Purification of lectins from their plant sources and determination of their sugar specificity become an important goal for the evaluation of their potential biomedical applications. Here, we report the affinity purification of a D-galactose specific lectin from the seeds of Meizotropis buteiformis Voight., 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 has 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 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: Objective of the present study is to purify a novel lectin upto 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 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 temperature from 00C to 500¬C. The purified lectin does not show any effects on its activities for metal ions tested and protein view report of the LC-MS/MS result analysis showed a 50% sequence similarity with that of 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 a heterodimeric and metal ion independent. The LC-MS/MS results suggested that the purified lectin has not been reported earlier.