Isolation and characterization of a 30 kD antifungal protein from seeds of Sorghum bicolor

An antifungal protein of about 30 000 Da was isolated from seeds of Sorghum bicolor L. using chromatographic techniques, including gel filtration, ion exchange, and high-performance liquid chromatography in a reverse-phase column. This protein (termed 30 kD protein) showed a minimal inhibitory concentration of 36 μg/ml for Candida parapsilosis and C. tropicalis, and 18 μg/ml for C. albicans. The 30 kD protein inhibited adherence to the cover glass and formation of a germinative tube of C. albicans at concentrations over 300 and 150 μg/ml, respectively. Transmission electron microscopy of yeast forms of C. albicans after incubation with 18 μg/ml of the 30 kD protein for 24 h revealed marked ultrastructural changes in the fungus. No toxicity of the 30 kD protein to the culture of Hep2 cells at concentrations equal to or less than 1000 μg/ml was observed.