title: Isolation and partial characterization of a new ribosome-inactivating protein from Petrocoptis glaucifolia (Lag.) Boiss.
abstract: Petrocoptis glaucifolia, a paleoendemic member of the Caryophyllaceae from the North of Spain, was found to contain at least five proteins that inhibit protein synthesis in a rabbit reticulocyte lysate. One of them, for which the name petroglaucin is proposed, was purified to apparent electrophoretic homogeneity by chromatography through S-Sepharose Fast Flow, Sephadex G-75 and CM-Sepharose Fast Flow. The apparent Mr of the preparation was 27500. This protein does not contain appreciable glycan chains and displays 45.8% of NH2-terminal amino-acid sequence homology with some ribosome-inactivating proteins from Saponaria officinalis, another member of the Caryophyllaceae. Petroglaucin shows the following functional properties: (i) it strongly inhibits the rabbit-reticulocyte-lysate system and Vicia sativa cell-free extracts, both coded by endogenous messengers, and also inhibits poly(U)-directed polyphenylalanine synthesis by Vicia sativa cell-free extracts and purified rat-liver ribosomes; (ii) it shows much less inhibitory capacity in wheat-germ, Cucumis sativus and rat-liver cell-free systems coded by endogenous messengers; (iii) the inhibitory effects on purified rat-liver ribosomes were irreversible; (vi) it promotes the release of adenine from purified rat-liver ribosomes. The total activity of this translational inhibitor has been found to increase up to 11-fold during its purification, indicating that some regulatory factor that normally blocks the translational inhibitory activity of the ribosome-inactivating protein in crude extracts of the plant is removed during purification.
authors.affiliation: Departamento de Bioquimica, Biologia Molecular y Fisiologia, Facultad de Ciencias, Universidad de Valladolid, E-47005, Valladolid.
authors.forename: F J
authors.initials: FJ
authors.lastname: Arias
authors.forename: M A
authors.initials: MA
authors.lastname: Rojo
authors.forename: J M
authors.initials: JM
authors.lastname: Ferreras
authors.forename: R
authors.initials: R
authors.lastname: Iglesias
authors.forename: R
authors.initials: R
authors.lastname: Muñoz
authors.forename: A
authors.initials: A
authors.lastname: Rocher
authors.forename: E
authors.initials: E
authors.lastname: Mendez
authors.forename: L
authors.initials: L
authors.lastname: Barbieri
authors.forename: T
authors.initials: T
authors.lastname: Girbés