Limlin, a novel leguminous peroxidase with antifungal activity from phaseolus limensis

Plants have been one of the hot research topics in the search for potent antifungals. The objective of this study was to isolate a novel antifungal protein from Phaseolus limensis. A protein designated Limlin, with both antifungal and antibacterial activity was isolated and characterized. The isolation procedure entailed extraction, precipitation, affinity chromatography on Affi-gel blue gel, ion chromatography on SP-Toyopearl and gel filtration on Sephadex G-75. The protein exhibited a molecular mass of 34 kDa in SDS-polyacrylamide gel electrophoresis both under reducing and non-reducing conditions. Its N-terminal sequence was determined as QNNPAGFKGDKANAMLKMGNLS-FQT, showing some homology to peroxidases and peroxidase precursors from plants. It potently suppressed mycelial growth of Fusarium solani, Mycosphaerella arachidicola and Pythium aphanidermatum. Moreover, this novel protein showed antiproliferative activity towards human liver hepatoma cells Bel-7402 and neuroblastoma cells SHSY5Y. This investigation first demonstrates an antifungal peroxidase with antiproliferative activity in large lima legume.