A ribosome inactivating protein demonstrating a molecular mass of 21 kDa and a novel N-terminal sequence was isolated from seeds of the hairy melon. The purification procedure involved affinity chromatography on Affi-gel blue gel and ion exchange chromatography on CM-Sepharose and Mono S. The protein designated hispin inhibited translation in the cell-free rabbit reticulocyte lysate system with an IC50 of 165 pM and exhibited N-glycosidase activity. Antifungal activity was also observed. (C) 2002 Elsevier Science (USA). All rights reserved.