scholarly journals Characterization of Ectophosphatase Activities in Trypanosomatid Parasites of Plants

2000 ◽  
Vol 90 (9) ◽  
pp. 1032-1038 ◽  
Author(s):  
P. M. L. Dutra ◽  
C. O. Rodrigues ◽  
A. Romeiro ◽  
L. A. M. Grillo ◽  
F. A. Dias ◽  
...  
Keyword(s):  
Lithium Fluoride ◽  
External Surface ◽  
Sodium Orthovanadate ◽  
Intact Cells ◽  
Phosphatase Activities ◽  
Cerium Phosphate ◽  
Cytochemical Analysis ◽  
Trypanosomatid Parasites ◽  
Phosphate Deposits

In the present work ectophosphatase activities of three trypanosomatid parasites of plants were characterized using intact cells. Phytomonas françai, Phytomonas mcgheei, and Herpetomonas sp. hydrolyzed p-nitro-phenylphosphate at a rate of 5.40, 7.28, and 25.58 nmol Pi/mg of protein per min, respectively. Experiments using classical inhibitors of acid phosphatases such as sodium orthovanadate (NaVO3) and sodium fluoride (NaF) showed a decrease in phosphatase activities. Lithium fluoride (LiF) and aluminum chloride (AlCl3) were also used. Although AlCl3 had no effect, LiF was able to promote a decrease in the phosphatase activities. Interestingly, the inhibition caused by LiF was enhanced by the addition of AlCl3 during the reaction, probably due to the formation of fluoroaluminate complexes. This effect was confirmed by cytochemical analysis. In this assay, electron-dense cerium phosphate deposits were visualized on the external surface of the three parasites.

scholarly journals Secreted Phosphatase Activities in Trypanosomatid Parasites of Plants Modulated by Platelet-Activating Factor

2001 ◽  
Vol 91 (4) ◽  
pp. 408-414 ◽  
Author(s):  
P. M. L. Dutra ◽  
F. A. Dias ◽  
M. A. A. Santos ◽  
C. O. Rodrigues ◽  
A. Romeiro ◽  
...  
Keyword(s):  
Phosphatase Activity ◽  
External Surface ◽  
Platelet Activating Factor ◽  
Sodium Orthovanadate ◽  
Flagellar Pocket ◽  
Sodium Tartrate ◽  
Phosphatase Activities ◽  
Cytochemical Analysis ◽  
Plant Parasite ◽  
Trypanosomatid Parasites

The secreted phosphatase activities of two trypanosomatid parasites were characterized and compared with supernatants of living cells. The plant parasite Phytomonas françai and the phytophagous hemipteran parasite Herpetomonas sp. hydrolyzed p-nitrophenylphosphate at a rate of 15.54 and 6.51 nmol Pi/mg of protein per min, respectively. Sodium orthovanadate (NaVO3) and sodium fluoride (NaF) decreased the phosphatase activities. The phosphatase activity of P. françai was drastically diminished (73% inhibition) in the presence of sodium tartrate, whereas the phosphatase activity of Herpetomonas sp. was inhibited by 23%. Cytochemical analysis showed the localization of these enzymes on the external surface and in the flagellar pocket of the two trypanosomatids. Sodium tartrate inhibited this reaction, confirming the biochemical data. Platelet-activating factor modulated the phosphatase activities, inhibiting P. françai activity and stimulating Herpetomonas sp. phosphatase activity.

scholarly journals Localization and Characterization of a Parotid Ca2+-Dependent Ecto-ATPase

1993 ◽  
Vol 4 (3) ◽  
pp. 415-419 ◽  
Author(s):  
F.J. Dowd ◽  
L.S. Li ◽  
J.E. Campbell ◽  
P.H. Cheung
Keyword(s):  
Substrate Specificity ◽  
Sodium Azide ◽  
Ruthenium Red ◽  
Sodium Orthovanadate ◽  
Intact Cells

Parotid acini were isolated and tested to further establish the presence of ecto-ATPase in the intact cells. Inhibitors were used to determine if the inhibitor profile of the ATPase was similar to that of a Ca2+-ATPase from parotid membranes identified previously as an ecto-ATPase. The Ca 2+-ATPase of intact cells was insensitive to oligomycin (10 μg/ml), N-ethylmaleimide (NEM) (0.1 m M), ruthenium red (0.1 m M), sodium azide (1 m M), and was inhibited approximately 22% by sodium orthovanadate (Na3VO4) (1 m M). This profile was similar to the Ca2+-ATPase of intact cells. Trifluoperazine (TFP) (0.1 m M) inhibited the enzyme in intact cells by approximately 32%. The nucleotide substrate specificity of the enzyme also reflected very closely the pattern seen in isolated membranes.

Characterization of NH4-montmorillonite coexisting with NH4Cl salt at different aggregation states. Application to Ceres.

2021 ◽  
Author(s):  
Victoria Munoz-Iglesias ◽  
Maite Fernández-Sampedro ◽  
Carolina Gil-Lozano ◽  
Laura J. Bonales ◽  
Oscar Ercilla Herrero ◽  
...  
Keyword(s):  
Environmental Conditions ◽  
Spectroscopic Data ◽  
External Surface ◽  
Deionized Water ◽  
Asteroid Belt ◽  
Aqueous Alteration ◽  
Dawn Mission ◽  
Main Asteroid Belt ◽  
Spectroscopic Signatures

<p>Ceres, dwarf planet of the main asteroid belt, is considered a relic ocean world since the Dawn mission discovered evidences of aqueous alteration and cryovolcanic activity [1]. Unexpectedly, a variety of ammonium-rich minerals were identified on its surface, including phyllosilicates, carbonates, and chlorides [2]. Although from the Dawn’s VIR spectroscopic data it was not possible to specify the exact type of phyllosilicates observed, montmorillonite is considered a good candidate owing to its ability to incorporate NH<sub>4</sub><sup>+</sup> in its interlayers [3]. Ammonium-rich phases are usually found at greater distances from the Sun. Hence, the study on their stability at environmental conditions relevant to Ceres’ interior and of its regolith can help elucidate certain ambiguities concerning the provenance of its precursor materials.</p> <p>In this study, it was investigated the changes in the spectroscopic signatures of the clay mineral montmorillonite after (a) being immersed in ammonium chloride aqueous solution and, subsequently, (b) washed with deionized water. After each treatment, samples were submitted to different environmental conditions relevant to the surface of Ceres. For one experiment, they were frozen overnight at 193 K, and then subjected to 10<sup>-5</sup> bar for up to 4 days in a Telstar Cryodos lyophilizer. For the other, they were placed inside the Planetary Atmospheres and Surfaces Chamber (PASC) [4] for 1 day at 100 K and 5.10<sup>-8</sup> bar. The combination of different techniques, i.e., Raman and IR spectroscopies, XRD, and SEM/EDX, assisted the assignment of the bands to each particular molecule. In this regard, the signatures of the mineral external surface were distinguished from the interlayered NH<sub>4</sub><sup>+ </sup>cations. The degree of compaction of the samples resulted crucial on their stability and spectroscopic response, being stiff smectites more resistant to low temperatures and vacuum conditions. In ground clay minerals, a decrease in the basal space with a redshift of the interlayered NH<sub>4</sub><sup>+</sup> IR band was measured after just 1 day of being exposed to vacuum conditions.</p> <p>Acknowledgments</p> <p>This work was supported by the Spanish MINECO projects ESP2017-89053-C2-1-P and PID2019-107442RB-C32, and the AEI project MDM‐2017‐0737 Unidad de Excelencia “María de Maeztu”.</p> <p>References</p> <p>[1] De Sanctis et al.,  Space Sci. Rev. 216, 60, 2020</p> <p>[2] Raponi et al., Icarus 320, 83,  2019</p> <p>[3] Borden and Giese, Clays Clay Miner. 49, 444, 2001</p> <p>[4] Mateo-Marti et al., Life 9, 72, 2019</p>

scholarly journals Characterization of Tar Deposits, Extraction and Sorption Properties

2016 ◽  
Vol 62 (2) ◽  
pp. 1-4
Author(s):  
Adrian Pryszcz ◽  
Barbora Grycová ◽  
Ivan Koutník ◽  
Veronika Blahůšková
Keyword(s):  
Storage Tank ◽  
Potassium Hydroxide ◽  
Surface Characterization ◽  
External Surface ◽  
Single Point ◽  
Experimental Part ◽  
Surface Areas ◽  
Plot Analysis ◽  
Bet Method

Abstract The main goal of this paper was to characterize and find a useful solution for the decomposition of tar deposits. For the experimental part, tar deposits, formed by polymerization and condensation reactions, were chosen from a storage tank for tars. At first the initial analyses of tar deposits (elemental, thermogravimetric, and calorimetric analyses) were performed. After the characterization, the tar deposits were extracted in the Soxhlet extractor by acetone, toluene, and quinolone and activated with potassium hydroxide. As the final step of this work, the sorption characterization on the 3Flex Surface Characterization Analyzer (Micromeritics) was performed. The specific surface area of the samples was evaluated using two methods - a single point measurement at p/p0=0.2 and BET method. Micropore and external surface areas were calculated based on a t-plot analysis (carbon black model).

Use of electrophoretic techniques and MALDI–TOF MS for rapid and reliable characterization of bacteria: analysis of intact cells, cell lysates, and “washed pellets”

2013 ◽  
Vol 405 (10) ◽  
pp. 3165-3175 ◽  
Author(s):  
Jiří Šalplachta ◽  
Anna Kubesová ◽  
Dana Moravcová ◽  
Marie Vykydalová ◽  
Sándor Süle ◽  
...  
Keyword(s):  
Intact Cells ◽  
Maldi Tof Ms ◽  
Cell Lysates ◽  
Maldi Tof ◽  
Electrophoretic Techniques ◽  
Tof Ms

Voltammetric characterization of the aerobic energy-dissipating nitrate reductase of Paracoccus pantotrophus: exploring the activity of a redox-balancing enzyme as a function of electrochemical potential

2007 ◽  
Vol 409 (1) ◽  
pp. 159-168 ◽  
Author(s):  
Andrew J. Gates ◽  
David J. Richardson ◽  
Julea N. Butt
Keyword(s):  
Nitrate Reductase ◽  
Nitrate Reduction ◽  
Reductase Activity ◽  
Electrochemical Potential ◽  
Intact Cells ◽  
Protein Film ◽  
Protein Film Voltammetry ◽  
Voltammetric Studies ◽  
Paracoccus Pantotrophus

Paracoccus pantotrophus expresses two nitrate reductases associated with respiratory electron transport, termed NapABC and NarGHI. Both enzymes derive electrons from ubiquinol to reduce nitrate to nitrite. However, while NarGHI harnesses the energy of the quinol/nitrate couple to generate a transmembrane proton gradient, NapABC dissipates the energy associated with these reducing equivalents. In the present paper we explore the nitrate reductase activity of purified NapAB as a function of electrochemical potential, substrate concentration and pH using protein film voltammetry. Nitrate reduction by NapAB is shown to occur at potentials below approx. 0.1 V at pH 7. These are lower potentials than required for NarGH nitrate reduction. The potentials required for Nap nitrate reduction are also likely to require ubiquinol/ubiquinone ratios higher than are needed to activate the H+-pumping oxidases expressed during aerobic growth where Nap levels are maximal. Thus the operational potentials of P. pantotrophus NapAB are consistent with a productive role in redox balancing. A Michaelis constant (KM) of approx. 45 μM was determined for NapAB nitrate reduction at pH 7. This is in line with studies on intact cells where nitrate reduction by Nap was described by a Monod constant (KS) of less than 15 μM. The voltammetric studies also disclosed maximal NapAB activity in a narrow window of potential. This behaviour is resistant to change of pH, nitrate concentration and inhibitor concentration and its possible mechanistic origins are discussed.

High-resolution crystal structure of Trypanosoma brucei pteridine reductase 1 in complex with an innovative tricyclic-based inhibitor

2020 ◽  
Vol 76 (6) ◽  
pp. 558-564
Author(s):  
Giacomo Landi ◽  
Pasquale Linciano ◽  
Giusy Tassone ◽  
Maria Paola Costi ◽  
Stefano Mangani ◽  
...  
Keyword(s):  
Trypanosoma Brucei ◽  
Neglected Tropical Diseases ◽  
Protozoan Parasite ◽  
Binding Mode ◽  
New Class ◽  
Hydrogen Bond Interactions ◽  
Promising Strategy ◽  
Trypanosomatid Parasites ◽  
Micromolar Range

The protozoan parasite Trypanosoma brucei is the etiological agent of human African trypanosomiasis (HAT). HAT, together with other neglected tropical diseases, causes serious health and economic issues, especially in tropical and subtropical areas. The classical antifolates targeting dihydrofolate reductase (DHFR) are ineffective towards trypanosomatid parasites owing to a metabolic bypass by the expression of pteridine reductase 1 (PTR1). The combined inhibition of PTR1 and DHFR activities in Trypanosoma parasites represents a promising strategy for the development of new effective treatments for HAT. To date, only monocyclic and bicyclic aromatic systems have been proposed as inhibitors of T. brucei PTR1 (TbPTR1); nevertheless, the size of the catalytic cavity allows the accommodation of expanded molecular cores. Here, an innovative tricyclic-based compound has been explored as a TbPTR1-targeting molecule and its potential application for the development of a new class of PTR1 inhibitors has been evaluated. 2,4-Diaminopyrimido[4,5-b]indol-6-ol (1) was designed and synthesized, and was found to be effective in blocking TbPTR1 activity, with a K i in the low-micromolar range. The binding mode of 1 was clarified through the structural characterization of its ternary complex with TbPTR1 and the cofactor NADP(H), which was determined to 1.30 Å resolution. The compound adopts a substrate-like orientation inside the cavity that maximizes the binding contributions of hydrophobic and hydrogen-bond interactions. The binding mode of 1 was compared with those of previously reported bicyclic inhibitors, providing new insights for the design of innovative tricyclic-based molecules targeting TbPTR1.

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