Purification and characterization of charantin, a napin-like ribosome-inactivating peptide from bitter gourd (Momordica charantia) seeds.
A peptide designated charantin, with a molecular mass of 9.7 kDa, was isolated from bitter gourd seeds. The procedure comprised affinity chromatography on Affi-gel blue gel, ion-exchange chromatography on Mono S and gel filtration on Superdex 75. The N-terminal sequence of charantin exhibited marked similarity to that of the 7.8-kDa napin-like peptide previously isolated from bitter gourd seeds. Charantin inhibited cell-free translation in a rabbit reticulocyte lysate system with an IC50 of 400 nm, a potency lower than that of the previously reported small ribosome-inactivating protein gamma-momorcharin (IC50 = 55 nm) which also exhibited an abundance of arginine and glutamate/glutamine residues. Charantin reacted positively in the N-glycosidase assay, yielding a band similar to that formed by the small ribosome-inactivating proteins gamma-momorcharin and luffin S.
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Department of Biochemistry, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China.
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D055516:2S Albumins, Plant; D000595:Amino Acid Sequence; D000818:Animals; D002474:Cell-Free System; D004591:Electrophoresis, Polyacrylamide Gel; D008969:Molecular Sequence Data; D029777:Momordica charantia / Q000737:chemistry*; D010455:Peptides / Q000737:chemistry*; D010940:Plant Proteins / Q000737:chemistry* / Q000302:isolation & purification*; D014176:Protein Biosynthesis; D011817:Rabbits; D012270:Ribosomes / Q000737:chemistry*; D012639:Seeds / Q000737:chemistry; D017386:Sequence Homology, Amino Acid
D055516:2S Albumins, Plant; D010455:Peptides; D010940:Plant Proteins; C050363:napin protein, Brassica napus