A novel sialic acid-specific lectin from Phaseolus coccineus seeds with potent antineoplastic and antifungal activities
Chen, Jing × Liu, Bo Ji, Na Zhou, Jing Van Damme, Els Balzarini, Jan Chen, Fang Bao, Jin-Ku #
Phytomedicine vol:16 issue:4 pages:352-360
A novel lectin (PCL) with specificity towards sialic acid was purified from Phaseolus coccineus L. (P. multiflorus willd) seeds using ion exchange chromatography on CM and DEAE-Sepharose, and gel filtration on Sephacryl S-200 column. PCL was a homodimer consisting of 29,831.265Da subunits as determined by gel filtration and MS. Also, PCL was a non-metaloprotein and its N-terminal 20-amino acid sequence, MASSALLSLALFLVLLTKAN, was determined. Subsequently, MTT method, cell morphological analysis and LDH activity-based cytotoxicity assays demonstrated that PCL was highly cytotoxic to L929 cells and induced apoptosis in a dose-dependent manner. Using caspase inhibitors, a typical caspase-dependent pathway was confirmed. PCL also showed remarkable antifungal activity towards some plant pathogenic fungi. Furthermore, when sialic acid-specific activity was fully inhibited, cytotoxicity and antifungal activity were abruptly decreased, respectively, suggesting a significant correlation between sialic acid-specific site and its bi-functional bioactivities.