Search results for "ATP"
showing 10 items of 736 documents
Polar/Ionizable Residues in Transmembrane Segments: Effects on Helix-Helix Packing
2012
The vast majority of membrane proteins are anchored to biological membranes through hydrophobic alpha-helices. Sequence analysis of high-resolution membrane protein structures show that ionizable amino acid residues are present in transmembrane (TM) helices, often with a functional and/or structural role. Here, using as scaffold the hydrophobic TM domain of the model membrane protein glycophorin A (GpA), we address the consequences of replacing specific residues by ionizable amino acids on TM helix insertion and packing, both in detergent micelles and in biological membranes. Our findings demonstrate that ionizable residues are stably inserted in hydrophobic environments, and tolerated in t…
Effects of sulindac sulfide on the membrane architecture and the activity of gamma-secretase.
2007
gamma-Secretase is a membrane-embedded multi-protein complex that catalyzes the final cut of the Alzheimer's disease-related amyloid precursor protein (APP) to amyloid-beta peptides of variable length (37-43 amino acids) via an unusual intramembrane cleavage. Recent findings propose that some commonly used non-steroidal anti-inflammatory drugs (NSAIDs) have the ability to modulate specifically gamma-secretase activity without inhibiting the enzyme as a whole. These drugs may shift the processing of APP from the longer amyloid-beta 42 peptide towards shorter, less fibrillogenic and less toxic amyloid-beta species. We hypothesize that gamma-secretase activity, as an enzyme that is strictly as…
Peroxisomal and mitochondrial status of two murine oligodendrocytic cell lines (158N, 158JP): potential models for the study of peroxisomal disorders…
2009
International audience; In some neurodegenerative disorders (leukodystrophies) characterized by myelin alterations, the defect of peroxisomal functions on myelin-producing cells (oligodendrocytes) are poorly understood. The development of in vitro models is fundamental to understanding the physiopathogenesis of these diseases. We characterized two immortalized murine oligodendrocyte cell lines: a normal (158N) and a jimpy (158JP) cell line mutated for the proteolipid protein PLP/DM20. Fluorescence microscopy, flow cytometry, and western blotting analysis allow to identify major myelin proteins (PLP colocalizing with mitochondria; myelin basic protein), oligodendrocyte (CNPase and myelin oli…
Differential changes in purine nucleotides after Doxorubicin treatment of human cancer cells in vitro
2002
The present investigation was performed to elucidate the role of purine nucleotides as potential indicators of chemosensitivity of malignant tumors. Drug-sensitive (s) and -resistant (r) tumor cell lines grown as monolayers (s: T47D, MCF-7 wild-type; r: NCI/ADR-RES, MCF-7/MDR) or as multicellular spheroids (T47D; NCI/ADR-RES) were exposed to 0.1, 1.0, and 10.0 microM Doxorubicin for up to 24 h. Purine nucleotides were assayed using HPLC and with some selected spheroids using imaging bioluminescence. The data show that in the time frame of the experiments reproducible and statistically significant changes in the nucleotides only occur at the highest drug concentration investigated. Under the…
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…
Darbinieku kontroles sistēma, izmantojot biometrijas datus
2019
Kvalifikācijas darba mērķis ir izstrādāt darbinieku kontroles sistēmu, kura izmanto biometrijas datus (sejas atpazīšanu), un ar kuras palīdzību var koordinēt un pārvaldīt firmas darbinieku darbības un to personīgos datus, un tas ļauj efektīvāk organizēt uzņēmuma darbību. Šī sistēma ir izveidota C++ programmēšanas valodā izmantojot QT Creator ietvaru un atvērtā koda bibliotēku OpenCv. Sistēmas dati tiek glabāti SQLite datubāzē. Sistēma tika veidota izmantojot gan ūdenskrituma (waterfall) modeli, gan spējas (agile) izstrādes metodes. Sistēma sastāv no 4 moduļiem - autentificēšanās, lietotāja, atpazīšanas, atskaišu.
A topological substructural approach for the prediction of P-glycoprotein substrates
2006
A topological substructural molecular design approach (TOPS-MODE) has been used to predict whether a given compound is a P-glycoprotein (P-gp) substrate or not. A linear discriminant model was developed to classify a data set of 163 compounds as substrates or nonsubstrates (91 substrates and 72 nonsubstrates). The final model fit the data with sensitivity of 82.42% and specificity of 79.17%, for a final accuracy of 80.98%. The model was validated through the use of an external validation set (40 compounds, 22 substrates and 18 nonsubstrates) with a 77.50% of prediction accuracy; fivefold full cross-validation (removing 40 compounds in each cycle, 80.50% of good prediction) and the predictio…
Emociju atpazīšanas un to kontroles veidošanās bērniem ar smagiem garīgās attīstības traucējumiem
2020
Emociju atpazīšanas un to kontroles veidošanās bērniem ar smagiem garīgās attīstības traucējumiem Diplomdarba autore: Irina Strogonova Diplomdarba vadītājs: docente Dr. paed. Ilze Šūmane Diplomdarba apjoms: 52 lpp., 5 tabulas, 15 attēli, 31 pielikums, izmantoti 47 literatūras avoti. Pētījuma mērķis: Izpētīt emociju atpazīšanu un to kontroli bērniem smagiem garīgās attīstības traucējumiem pedagoģiskos apstākļos mācību un audzināšanas procesā. Pētījuma jautājumi: 1.Vai izstrādāto metodisko pieeju izmantošana 4. klases skolēniem ar smagiem GAT 5 mēnešus ilgā laika posmā nodrošina pozitīvas izmaiņas emociju atpazīšanā un to kontrolē? 2.Kuras izvēlētās metodes bija visefektīvākās un kuras radīja…
Survival of Listeria monocytogenes in Soil Requires AgrA-Mediated Regulation
2015
ABSTRACT In a recent paper, we demonstrated that inactivation of the Agr system affects the patterns of survival of Listeria monocytogenes (A.-L. Vivant, D. Garmyn, L. Gal, and P. Piveteau, Front Cell Infect Microbiol 4:160, http://dx.doi.org/10.3389/fcimb.2014.00160 ). In this study, we investigated whether the Agr-mediated response is triggered during adaptation in soil, and we compared survival patterns in a set of 10 soils. The fate of the parental strain L. monocytogenes L9 (a rifampin-resistant mutant of L. monocytogenes EGD-e) and that of a Δ agrA deletion mutant were compared in a collection of 10 soil microcosms. The Δ agrA mutant displayed significantly reduced survival in these b…
Role of ΔpH in the mechanism of zeaxanthin-dependent amplification of qE
1995
Abstract The influence of zeaxanthin on the high-energy-state fluorescence quenching (qE) and the pH dependence of the maximum chlorophyll fluorescence yield (Fm) was examined in spinach thylakoids. High contents of zeaxanthin were achieved using different pretreatments. A pronounced, zeaxanthin-dependent amplification of non-photochemical quenching (NPQ) was exclusively found in thylakoids containing zeaxanthin, synthesized in the dark via the buildup of an artificial ΔpH. These thylakoids also showed a significant quenching of chlorophyll fluorescence in the range pH 5.5–6.3, where no or only slight quenching was visible in zeaxanthin-free thylakoids. Thylakoids containing high amounts of…