title: Isolation of a novel Kunitz family protease inhibitor in association with Tethya hemolysin from the sponge Tethya ingalli.
abstract: Aqueous extracts from the New Zealand sponge Tethya ingalli (Hadromerida) displayed potent cytotoxicity in the NCI's 60-cell-line human tumor panel. Fractionation of the extract by ammonium sulfate precipitation, gel filtration, ultrafiltration, and both hydrophobic interaction and reversed-phase chromatography resulted in the isolation of two biologically active proteins. The first protein, Tethya protease inhibitor (TPI), which was purified to homogeneity, inhibited trypsin with an EC50 of 65 nM. TPI had a molecular mass of 11,431 Da, and an isoelectric point of 8.2. A partial N-terminal amino acid sequence determined for TPI showed significant homology with protease inhibitors of the Kunitz family. The second isolated protein displayed potent cytotoxicity, with pronounced selectivity for certain tumor cell lines (e.g., ovarian, renal, CNS, and breast). The latter protein, which had an apparent molecular weight of 21 kDa (SDS-PAGE), also lysed human red blood cells (EC50 of 39 nM) and was similar to a hemolysin previously isolated from the sponge Tethya lycinurium.
authors.affiliation: Laboratory of Drug Discovery Research and Development, NCI-Frederick Cancer Research and Development Center, Maryland 21702-1201, USA.
authors.forename: B R
authors.initials: BR
authors.lastname: O'Keefe
authors.forename: J A
authors.initials: JA
authors.lastname: Beutler
authors.forename: J H
authors.initials: JH
authors.lastname: Cardellina
authors.forename: T R
authors.initials: TR
authors.lastname: Prather
authors.forename: R H
authors.initials: RH
authors.lastname: Shoemaker
authors.forename: R C
authors.initials: RC
authors.lastname: Sowder
authors.forename: L E
authors.initials: LE
authors.lastname: Henderson
authors.forename: L K
authors.initials: LK
authors.lastname: Pannell
authors.forename: M R
authors.initials: MR
authors.lastname: Boyd
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002470:Cell Survival / Q000187:drug effects; D004910:Erythrocyte Membrane / Q000378:metabolism; D006384:Hemagglutination; D006461:Hemolysis; D006801:Humans; D066298:In Vitro Techniques; D007525:Isoelectric Focusing; D008969:Molecular Sequence Data; D011161:Porifera / Q000201:enzymology*; D011480:Protease Inhibitors / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D014407:Tumor Cells, Cultured
chemical_list: D000596:Amino Acids; D011480:Protease Inhibitors