Search results for "Pyrophosphatase"
showing 10 items of 16 documents
Cercospora beticola toxins. Part XVII. The role of the beticolin/Mg2+ complexes in their biological activity Study of plasma membrane H+-ATPase, vacu…
1996
Beticolin-1 and beticolin-2, yellow toxins produced by the phytopathogenic fungus Cercospora beticola, inhibit the plasma membrane H(+)-ATPase. Firstly, since beticolins are able to form complexes with Mg2+, the role of the beticolin/Mg2+ complexes in the inhibition of the plasma membrane proton pump has been investigated. Calculations indicate that beticolins could exist under several forms, in the H(+)-ATPase assay mixture, both free or complexed with Mg2+. However, the percentage inhibition of the H(+)-ATPase activity is correlated to the concentration of one single form of beticolin, the dimeric neutral complex Mg2H2B2, which appears to be the active form involved in the H(+)-ATPase inh…
Influence of ATPase activity on PPi dependent H+-transport in tonoplast vesicles of Acer pseudoplatanus
1994
Abstract Tonoplast H + -ATPase and H + -pyrophosphatase (H + -PPase) were previously characterized in Acer pseudoplatanus cells (A. Pugin et al., Plant Sci., 73 (1991) 23–34; A. Fraichard et al., Plant Physiol. Biochem., 31 (1993) 349–359). The present study concerns the relationships between these two enzymes in vitro. ATP and PPi hydrolysis were additive and the inhibition of one did not affect the activity of the second one. ATP and PPi H + -transports were also additive. The H + -PPase inhibition did not change ATP-dependent H + -transport but H + -ATPase inhibition inhibited the PPi dependent H + -transport. Because H + -PPase was reported to transport H + and K + into the vacuole (Dav…
Inorganic Polyphosphate in Human Osteoblast-like Cells
1998
Significant amounts of inorganic polyphosphates and of polyphosphate-degrading exopolyphosphatase activity were detected in human mandibular-derived osteoblast-like cells. The amount of both soluble and insoluble long-chain polyphosphate in unstimulated osteoblast-like cells was higher than in human gingival cells, erythrocytes, peripheral blood mononuclear cells, and human blood plasma. The cellular content of polyphosphate in osteoblast-like cells strongly decreased after a combined treatment of the cells with the stimulators of osteoblast proliferation and differentiation, dexamethasone, beta-glycerophosphate, epidermal growth factor, and ascorbic acid. The amount of soluble long-chain p…
Occupational exposure to metal-rich particulate matter modifies the expression of repair genes in foundry workers
2021
Foundry workers are exposed to numerous occupational health hazards, which may result in increased risk of cancer, respiratory disease, and other diseases. Oxidative stress is known to be involved in the pathogenesis of such diseases. The present study aimed to investigate the association between multiple occupational exposures in foundry workers and expression of deoxyribonucleic acid (DNA) repair genes as a biomarker of oxidative DNA damage. The study sample comprised 17 foundry workers and 27 matched control subjects. Expression of 8-oxoguanine DNA glycosylase-1 (OGG1), inosine triphosphate pyrophosphate (ITPA), and MutT homolog 1 (MTH1) in peripheral blood was examined using the real-t…
Lipid nanoparticles as delivery vehicles for the Parietaria judaica major allergen Par j 2
2011
Maria Luisa Bondì1,*, Giovanna Montana2,*, Emanuela Fabiola Craparo3, Roberto Di Gesù3, Gaetano Giammona3, Angela Bonura2, Paolo Colombo21Istituto per lo Studio dei Materiali Nanostrutturati, 2Istituto di Biomedicina ed Immunologia Molecolare, Consiglio Nazionale delle Ricerche, 3Laboratory of Biocompatible Polymers, Dipartimento di Scienze e Tecnologie Molecolari e Biomolecolari Stembio, Università di Palermo, Palermo, Italy *These authors contributed equally to this workAbstract: Parietaria pollen is one of the major causes of allergic reaction in southern Europe, affecting about 30% of all allergic patients in this area. Specific immunotherapy is the only…
Immunological detection of tonoplast polypeptides in the plasma membrane of pea cotyledons
1996
The tonoplast is usually characterized by the presence of two electrogenic proton pumps: a vacuolartype H+-ATPase and a pyrophosphatase, as well as a putative water-channel-forming protein (γ-TIP). Using a post-embedding immunogold labelling technique, we have detected the presence of these transport-protein complexes not only in the tonoplast, but also in the plasma membrane and trans Golgi elements of maturing pea (Pisum sativum L.) cotyledons. These ultrastructural observations are supported by Western blotting with highly purified plasma-membrane fractions. In contrast to the vacuolar-type H+-ATPase, whose activity was not measurable, considerable pyrophosphatase activity was detected i…
Distinct lytic vacuolar compartments are embedded inside the protein storage vacuole of dry and germinating Arabidopsis thaliana seeds.
2011
International audience; Plant cell vacuoles are diverse and dynamic structures. In particular, during seed germination, the protein storage vacuoles are rapidly replaced by a central lytic vacuole enabling rapid elongation of embryo cells. In this study, we investigate the dynamic remodeling of vacuolar compartments during Arabidopsis seed germination using immunocytochemistry with antibodies against tonoplast intrinsic protein (TIP) isoforms as well as proteins involved in nutrient mobilization and vacuolar acidification. Our results confirm the existence of a lytic compartment embedded in the protein storage vacuole of dry seeds, decorated by γ-TIP, the vacuolar proton pumping pyrophospha…
Allosteric regulation by Mg2+ of the vacuolar H(+)-PPase from Acer pseudoplatanus cells. Ca2+/Mg2+ interactions.
1996
The tonoplast H(+)-PPase was previously characterized in Acer pseudoplatanus cells (Pugin et al (1991) Plant Sci 73, 23-34; Fraichard et al (1993) Plant Physiol Biochem 31, 349-359). Tonoplast vesicles were obtained from vacuoles isolated from protoplasts of A pseudoplatanus suspension cultures and used to study kinetic effects of Mg2+ and Ca2+ on PPi hydrolysis. The concentrations of ionic species (free Mg2+, free PPi, and MgPPi complexes) were calculated with apparent dissociation constants of 55.3 microM for MgPPi and 59.6 microM for CaPPi. Our results indicated that the substrate of the tonoplast PPase was a MgPPi complex and that free Mg2+ was essential for PPi hydrolysis. With fixed f…
Theoretical study of phosphodiester hydrolysis in nucleotide pyrophosphatase/phosphodiesterase. Environmental effects on the reaction mechanism.
2010
We here present a theoretical study of the alkaline hydrolysis of methyl p-nitrophenyl phosphate (MpNPP(-)) in aqueous solution and in the active site of nucleotide pyrophosphatase/phosphodiesterase (NPP). The analysis of our simulations, carried out by means of hybrid quantum mechanics/molecular mechanics (QM/MM) methods, shows that the reaction takes place through different reaction mechanisms depending on the environment. Thus, while in aqueous solution the reaction occurs by means of an A(N)D(N) mechanism, the enzymatic process takes place through a D(N)A(N) mechanism. In the first case, we found associative transition-state (TS) structures, while in the enzyme TS structures have dissoc…
Transformation of Amorphous Polyphosphate Nanoparticles into Coacervate Complexes: An Approach for the Encapsulation of Mesenchymal Stem Cells.
2018
Inorganic polyphosphate [polyP] has proven to be a promising physiological biopolymer for potential use in regenerative medicine because of its morphogenetic activity and function as an extracellular energy-donating system. Amorphous Ca2+ -polyP nanoparticles [Ca-polyP-NPs] are characterized by a high zeta potential with -34 mV (at pH 7.4). This should contribute to the stability of suspensions of the spherical nanoparticles (radius 94 nm), but make them less biocompatible. The zeta potential decreases to near zero after exposure of the Ca-polyP-NPs to protein/peptide-containing serum or medium plus serum. Electron microscopy analysis reveals that the particles rapidly change into a coacerv…