EXTRACTION, PURIFICATION AND CHARACTERIZATION OF LECTIN FROM PHASEOLUS VULGARIS L. CV. WHITE SEEDS (WHITE KIDNEY BEAN) Basheer A. AL-ALWANI, Mohammed A. JEBOR, Yasser H. JALIL University of Babylon, College of Science, Department of Biology, Box.4, Hilla, Iraq Corresponding author email: mohammed622005@yahoo.com Abstract The purpose of the research was to study the purification and characterization of lectin from Phaseolus vulgaris L. cv.white seeds. The lectin was purified by sequence of steps , namly , first with ammonium sulfate precipitation followed by ion exchange (DEAE cellulose) and gel filtration (sephadex G-200) chromatographies , and finally by polyacrylamide electrophoresis (PAGE). Single band was observed in native PAGE . The lectin was shown to have molecular weight of 33 kDa in SDS PAGE and about 35 kDa in gel filtration and purified about 9.01 fold to final specific activity of 64 titer/mg of protein. The hemagglutination activity of the lectin was stable within the pH range from 4-11 and temperature range from 0°-50°C. Chemical modification results indicate that lysine and tryptophan were crucial for the hemagglutination activity of lectin. The results of carbohydrates specificity showed that the lectin was had complex sugar specifities, but not specific to xylose and mannose. Keywords: lactin, purification, characterization, Phaseolus vulgaris L. INTRODUCTION Lectins are defined as proteins/glycoproteins possessing at least one non-catalytic domain which binds reversibly to a specific mono-or oligosaccharide (Van damme et al., 2003). Over the last few decades, lectins have become a topic of interest to a large number of researchers owing to their potentially exploitable biological properties including antitumor (Abdullaev et al., 1997; Ye et al., 2001), immunomodulatory and anti-insect (Rubinstein et al., 2004), antifungal (Barrientos et al., 2005), antibacterial (Pusztai et al., 1993), anti-HIV (Tsang et al., 2001; Barrientos et al., 2005; Pollicita et al., 2008), and mitogenic (Wimer, 1990) activities. Because of their sugar binding properties, lectins have been extensively studied and used as molecular tools for the study of carbohydrate architecture and dynamics on the cell surface, and have been exploited for such practical applications as distinguishing between normal and malignant cells (Sharon, 1993; Padma et al., 1998), purification of glycoconjugates (Yamamoto et al., 1984), and coating of drugs to enhance their gastrointestinal tract absorption (Naisbett & Woodley, 1990; Leher, 2000). Further, specific amino acid residues are essential for maintaining the carbohydrate binding and hemagglutinating activities of lectins (Bao et al., 1996; Ba˘i˘miev et al., 2007). Identification of these amino acid residues is a prerequisite for investigating the structure-function relationships of lectins. Chemical modification with group-specific modifying agents provides a general approach for identification of the amino acid residues present in the functional or active site of proteins, including lectins (Bao et al., 1996; Nadimpalli, 1999). Hence, elucidation of biological activities of lectins and amino acid residues essential to these activities is a meaningful undertaking. Although lectins are found ubiquitously in plant species, they have variable structures and specific activities according to the plants they originate from cells (Sharon, 1993; Padma et al., 1998). Thus, purification and characterization of lectins from a variety of plant species interests researchers in the field of glycobiology. The more is known about the lectins, the wider the applications of this type of proteins that can be achieved. This study reports the purification and some properties of a new lectin isolated from seeds of the Phaseolus vulgaris L. cv.white cultivar (common name, white kidney bean). To date, the isolation of a lectin from the Phaseolus 69 Scientific Bulletin. Series F. Biotechnologies, Vol. XVII, 2013 ISSN 2285-1364, CD-ROM ISSN 2285-5521, ISSN Online 2285-1372, ISSN-L 2285-1364