title: Cochinin B, a novel ribosome-inactivating protein from the seeds of Momordica cochinchinensis.
abstract: Cochinin B, a novel ribosome-inactivating protein (RIP) with a molecular weight of 28 kDa, was purified from the seeds of Momordica cochinchinensis (Cucurbitaceae). The isolation procedure entailed ammonium sulfate precipitation, cation-exchange chromatography on SP Sepharose column and size-exclusion chromatography on Superdex 75 column with a fast protein liquid chromatography (FPLC) system. The first twenty N-terminal amino acid residues of Cochinin B showed homology to type I RIPs from other Momordica species. The purified Cochinin B displayed a strong inhibitory activity on protein synthesis in the cell-free rabbit reticulocyte lysate system with IC50 of 0.36 nM. Furthermore, it exhibited N-glycosidase activity and cytotoxicity against Vero cell line with IC50 higher than 1540 nM. Interestingly, Cochinin B manifested strong anti-tumor activities on human cervical epithelial carcinoma (HeLa), human embryonic kidney (HEK293) and human small cell lung cancer (NCI-H187) cell lines with IC50 of 16.9, 114 and 574 nM, respectively.
authors.affiliation: Department of Biochemistry, Faculty of Pharmacy, Mahidol University.
authors.forename: Juthamas
authors.initials: J
authors.lastname: Chuethong
authors.forename: Kohei
authors.initials: K
authors.lastname: Oda
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Sakurai
authors.forename: Ikuo
authors.initials: I
authors.lastname: Saiki
authors.forename: Wichet
authors.initials: W
authors.lastname: Leelamanit
mesh_terms: D000818:Animals; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002474:Cell-Free System; D002522:Chlorocebus aethiops; D004591:Electrophoresis, Polyacrylamide Gel; D006367:HeLa Cells; D006801:Humans; D020128:Inhibitory Concentration 50; D029775:Momordica / Q000737:chemistry*; D010940:Plant Proteins / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D014176:Protein Biosynthesis / Q000187:drug effects; D011817:Rabbits; D012156:Reticulocytes / Q000378:metabolism; D012270:Ribosomes / Q000187:drug effects / Q000378:metabolism; D012639:Seeds / Q000737:chemistry*; D020539:Sequence Analysis, Protein; D014709:Vero Cells
chemical_list: D010940:Plant Proteins