Purification and characterization of alpha- and beta-benincasins,arginine/glutamate-rich peptides with translation-inhibiting activity from wax gourd seeds

Two peptides, with a molecular mass of about 11 kDa and an N-terminal sequence abundant in arginine and glutamine residues, were isolated from wax gourd seeds. The isolation protocol included affinity chromatography on Affi-gel blue gel, ion-exchange chromatography on Mono-S and gel filtration on Superdex 75. The peptides, designated alpha- and beta-benincasins, inhibited cell-free translation in a rabbit reticulocyte lysate system with an IC(50) of 20 and 320 pM, respectively. Alpha-benincasin exhibited weak antifungal activity toward Coprinus comatus and Physalospora piricola but not toward Mycosphaerella arachidicola.