Investigation of binuclear metal phthalocyanines as electrocatalysts for Li/SOCl<Subscript>2</Subscript> battery

Three novel series of the binuclear metal phthalocyanines M₂Pc₂, M₂Pc₂Hc, and M₂Nc₂ (M?=?Mn(II), Fe(II), Co(II), Ni(II), and Cu(II)) were synthesized and characterized. The electrocatalytic performance of the binuclear compounds to lithium–thionyl chloride battery was evaluated by operating these compounds in the electrolyte of the battery. The results indicated that the binuclear metal phthalocyanines improved the capacity of the battery by an increase of approximately 30–58 %. Of all, Cu₂Pc₂Hc and Fe₂Nc₂ displayed the highest increments of 56 and 57 %, respectively.     

Effect of the expression and knockdown of citrate synthase gene on carbon flux during triacylglycerol biosynthesis by green algae <Emphasis Type="Italic">Chlamydomonas reinhardtii</Emphasis>

Background

The regulation of lipid biosynthesis is essential in photosynthetic eukaryotic cells. This regulation occurs during the direct synthesis of fatty acids and triacylglycerols (TAGs), as well as during other controlling processes in the main carbon metabolic pathway.

Results

In this study, the mRNA levels of Chlamydomonas citrate synthase (CrCIS) were found to decrease under nitrogen-limited conditions, which suggests suppressed gene expression. Gene silencing by RNA interference (RNAi) was conducted to determine whether CrCIS suppression affected the carbon flux in TAG biosynthesis. Results showed that the TAG level increased by 169.5%, whereas the CrCIS activities in the corresponding transgenic algae decreased by 16.7% to 37.7%. Moreover, the decrease in CrCIS expression led to the increased expression of TAG biosynthesis-related genes, such as acyl-CoA:diacylglycerol acyltransferase and phosphatidate phosphatase. Conversely, overexpression of CrCIS gene decreased the TAG level by 45% but increased CrCIS activity by 209% to 266% in transgenic algae.

Conclusions

The regulation of CrCIS gene can indirectly control the lipid content of algal cells. Our findings propose that increasing oil by suppressing CrCIS expression in microalgae is feasible.

     

KCTD20, a relative of BTBD10, is a positive regulator of Akt

Background

BTBD10 binds to Akt and protein phosphatase 2A (PP2A) and inhibits the PP2A-mediated dephosphorylation of Akt, thereby keeping Akt activated. Previous studies have suggested that BTBD10 plays an important role in preventing motor neuronal death and accelerating the growth of pancreatic beta cells. Because levels of BTBD10 expression are much lower in many non-nervous tissues than nervous tissues, there may be a relative of BTBD10 that has BTBD10-like function in non-neuronal cells.

Results

A 419-amino-acid BTBD10-like protein, named KCTD20 (potassium channel tetramerization protein domain containing 20), was to found to bind to all Akt isoforms and PP2A. Overexpression of KCTD20 increased Akt phosphorylation at Thr308, as BTBD10 did, which suggests that KCTD20 as well as BTBD10 positively regulates the function of Akt. KCTD20 was ubiquitously expressed in non-nervous as well as nervous tissues.

Conclusions

KCTD20 is a positive regulator of Akt and may play an important role in regulating the death and growth of some non-nervous and nervous cells.

     

Detrimental effect of the 6 His C-terminal tag on YedY enzymatic activity and influence of the TAT signal sequence on YedY synthesis

Background

YedY, a molybdoenzyme belonging to the sulfite oxidase family, is found in most Gram-negative bacteria. It contains a twin-arginine signal sequence that is cleaved after its translocation into the periplasm. Despite a weak reductase activity with substrates such as dimethyl sulfoxide or trimethylamine N-oxide, its natural substrate and its role in the cell remain unknown. Although sequence conservation of the YedY family displays a strictly conserved hydrophobic C-terminal residue, all known studies on Escherichia coli YedY have been performed with an enzyme containing a 6 histidine-tag at the C-terminus which could hamper enzyme activity.

Results

In this study, we demonstrate that the tag fused to the C-terminus of Rhodobacter sphaeroides YedY is detrimental to the enzyme’s reductase activity and results in an eight-fold decrease in catalytic efficiency. Nonetheless this C-terminal tag does not influence the properties of the molybdenum active site, as assayed by EPR spectroscopy. When a cleavable His-tag was fused to the N-terminus of the mature enzyme in the absence of the signal sequence, YedY was expressed and folded with its cofactor. However, when the signal sequence was added upstream of the N-ter tag, the amount of enzyme produced was approximately ten-fold higher.

Conclusion

Our study thus underscores the risk of using a C-terminus tagged enzyme while studying YedY, and presents an alternative strategy to express signal sequence-containing enzymes with an N-terminal tag. It brings new insights into molybdoenzyme maturation in R. sphaeroides showing that for some enzymes, maturation can occur in the absence of the signal sequence but that its presence is required for high expression of active enzyme.

     

Comparison of comet assay parameters for estimation of genotoxicity by sum of ranking differences

The genotoxic potential of waters in six rivers and reservoirs from Serbia was monitored in different tissues of chub (Squalius cephalus L. 1758) with the alkaline comet assay. The comet assay, or single-cell gel electrophoresis, has a wide application as a simple and sensitive method for evaluating DNA damage in fish exposed to various xenobiotics in the aquatic environment. Three types of cells, erythrocytes, gill cells, and liver cells, were used for assessing DNA damage. Images of randomly selected cells were analyzed with a Leica fluorescence microscope and image analysis by software (Comet Assay IV Image analysis system, PI, UK). Three parameters (tail length—l, tail intensity—i, and Olive tail moment—m) were analyzed on 1,700 nuclei per cell type. The procedure for sum of ranking differences (SRD) was implemented to compare different types of cells and different parameters for estimation of DNA damage. Regarding our nine different estimations of genotoxicity: tail length, intensity, and moment in erythrocytes (rel, rei, rem), liver cells (rll, rli, rlm), and gill cells (rgl, rgi, rgm), the SRD procedure has shown that the Olive tail moment and tail intensity are (almost) equally good parameters; the SRD value was lower for the tail moment and tail intensity than for tail length in the case of all types of cells. The least reliable parameter was rel; close to the borderline case were rei, rll, and rgl (～5 % probability of random ranking).

Targeting prohibited substances in doping control blood samples by means of chromatographic–mass spectrometric methods

Urine samples have been the predominant matrix for doping controls for several decades. However, owing to the complementary information provided by blood (as well as serum or plasma and dried blood spots (DBS)), the benefits of its analysis have resulted in continuously increasing appreciation by anti-doping authorities. On the one hand, blood samples allow for the detection of various different methods of blood doping and the abuse of erythropoiesis-stimulating agents (ESAs) via the Athlete Biological Passport; on the other hand, targeted and non-targeted drug detection by means of chromatographic–mass spectrometric methods represents an important tool to increase doping control frequencies out-of-competition and to determine drug concentrations particularly in in-competition scenarios. Moreover, blood analysis seldom requires in-depth knowledge of drug metabolism, and the intact substance rather than potentially unknown or assumed metabolic products can be targeted. In this review, the recent developments in human sports drug testing concerning mass spectrometry-based techniques for qualitative and quantitative analyses of therapeutics and emerging drug candidates are summarized and reviewed. The analytical methods include both low and high molecular mass compounds (e.g., anabolic agents, stimulants, metabolic modulators, peptide hormones, and small interfering RNA (siRNA)) determined from serum, plasma, and DBS using state-of-the-art instrumentation such as liquid chromatography (LC)–high resolution/high accuracy (tandem) mass spectrometry (LC-HRMS), LC–low resolution tandem mass spectrometry (LC-MS/MS), and gas chromatography–mass spectrometry (GC-MS).     

Simple and efficient one-pot solvent-free synthesis of N-methyl imines of aromatic aldehydes

A one-pot solvent-free synthesis of N-methyl imines in good to excellent yields was performed by grinding together aromatic aldehydes and methylamine hydrochloride in the presence of a base. The best yields were achieved when an excess of methylamine hydrochloride and inexpensive sodium hydrogen carbonate was used (usually in a molar ratio ArCHO/CH₃NH₂·HCl/NaHCO₃ = 1:5:5), allowing the reaction to proceed for 1 h (in the case of aromatic aldehydes containing electron-withdrawing substituents) or overnight (in the case of electron-rich aldehydes). After a simple work-up (extraction with diethyl ether) the obtained products were mostly pure enough for spectral characterization. In this way, 31 N-methyl imines were prepared, among which eight were synthesized for the first time. Their structures were elucidated by spectral means (¹H- and ¹³C-NMR, IR, MS) whenever it was possible. In the case of salicylaldehyde and 4-chlorobenzaldehyde, the synthesis of the corresponding imines was also conducted on a gram-scale with a 72% and 84% isolated yield, respectively. The present approach not only provides good to high yields, but also eliminates the disadvantages of the traditional synthesis of N-methyl imines, such as the use of hazardous solvents and more or less expensive catalysts and the necessity of work/handling with an anhydrous gas in pressurized containers.     

“On-water” organic synthesis: <Emphasis Type="SmallCaps">l</Emphasis>-proline catalyzed synthesis of pyrimidine-2,4-dione-, benzo[<Emphasis Type="Italic">g</Emphasis>]- and dihydropyrano[2,3-<Emphasis Type="Italic">g</Emphasis>]chromene derivatives in aqueous media

In this work, functionalized pyrimidine-2,4-dione-, benzo[g]-, and dihydropyrano[2,3-g]chromene derivatives have been synthesized via a Michael addition of 2-hydroxy-1,4-naphthoquinone or 2,5-dihydroxy-1,4-benzoquinone to the Knoevenagel condensation product of an aldehyde with Meldrum’s acid, dimedone or barbituric acid in the presence of a catalytic amount of l-proline under refluxing conditions in water in good to excellent yields.     

Characterization of <Emphasis Type="Italic">Pf</Emphasis>TrxR inhibitors using antimalarial assays and <Emphasis Type="Italic">in silico</Emphasis>techniques

Background

The compounds 1,4-napthoquinone (1,4-NQ), bis-(2,4-dinitrophenyl)sulfide (2,4-DNPS), 4-nitrobenzothiadiazole (4-NBT), 3-dimethylaminopropiophenone (3-DAP) and menadione (MD) were tested for antimalarial activity against both chloroquine (CQ)-sensitive (D6) and chloroquine (CQ)-resistant (W2) strains of Plasmodium falciparum through an in vitro assay and also for analysis of non-covalent interactions with P. falciparum thioredoxin reductase (PfTrxR) through in silico docking studies.

Results

The inhibitors of PfTrxR namely, 1,4-NQ, 4-NBT and MD displayed significant antimalarial activity with IC₅₀ values of?<?20 μM and toxicity against 3T3 cell line. 2,4-DNPS was only moderately active. In silico docking analysis of these compounds with PfTrxR revealed that 2,4-DNPS, 4-NBT and MD interact non-covalently with the intersubunit region of the enzyme.

Conclusions

In this study, tools for the identification of PfTrxR inhibitors using phenotyphic screening and docking studies have been validated for their potential use for antimalarial drug discovery project.

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