Luffangulin, a novel ribosome inactivating peptide from ridge gourd (Luffa acutangula) seeds.

A ribosome inactivating peptide, with an N-terminal sequence exhibiting pronounced similarity to that of the 6.5 kDa-arginine/glutamate-rich polypeptide from Luffa cylindrica seeds, was isolated from seeds of a closely related species, the ridge gourd Luffa acutangula. The 5.6 kDa-peptide designated luffangulin inhibited cell-free translation with an IC50 of 3.5 nM but lacked inhibitory activity toward HIV-1 reverse transcriptase. It was similar to luffaculin, the 28 kDa ribosome inactivating protein in being unadsorbed on DEAE-cellulose and adsorbed on Affi-gel blue gel. On CM-cellulose luffangulin and luffaculin appeared as two adjacent peaks.