Calcium ions effectively enhance the effect of antisense peptide nucleic acids conjugated to cationic tat and oligoarginine peptides

Cell-penetrating peptides have been widely used to improve cellular delivery of a variety of proteins and antisense agents. However, recent studies indicate that such cationic peptides are predominantly entering cells via an endosomal pathway. We now show that the nuclear antisense effect in HeLa cells of a variety of peptide nucleic acid (PNA) peptide conjugates is significantly enhanced by addition of 6 mM Ca(2+) (as well as by the lysosomotrophic agent chloroquine). In particular, the antisense activities of Tat(48-60) and heptaarginine-conjugated PNAs were increased 44-fold and 8.5-fold, respectively. Evidence is presented that the mechanism involves endosomal release. The present results show that Ca(2+) can be used as an effective enhancer for in vitro cellular delivery of cationic peptide-conjugated PNA oligomers, and also emphasize the significance of the endosomal escape route for such peptides.     

3D HCCH3-TOCSY for Resonance Assignment of Methyl-Containing Side Chains in C-Labeled Proteins

Two 3D experiments, (H)CCH₃-TOCSY and H(C)CH₃-TOCSY, are proposed for resonance assignment of methyl-containing amino acid side chains. After the initial proton–carbon INEPT step, during which either carbon or proton chemical shift labeling is achieved (t₁), the magnetization is spread along the amino acid side chains by a carbon spin lock. The chemical shifts of methyl carbons are labeled (t₂) during the following constant time interval. Finally the magnetization is transferred, in a reversed INEPT step, to methyl protons for detection (t₃). The proposed experiments are characterized by high digital resolution in the methyl carbon dimension (t_2max = 28.6 ms), optimum sensitivity due to the use of proton decoupling during the long constant time interval, and an optional removal of CH₂, or CH₂ and CH, resonances from the F₂F₃ planes. The building blocks used in these experiments can be implemented in a range of heteronuclear experiments focusing on methyl resonances in proteins. The techniques are illustrated using a ¹⁵N, ¹³C-labeled E93D mutant of Schizosacharomyces pombe phosphoglycerate mutase (23.7 kDa).     

Spectroscopic methods for determination of catecholamines: A mini-review

Catecholamines are biogenic compounds that perform a variety of vital functions, playing a key physiological role in humans and animals. They are important markers in diagnosis of diseases and dysfunctions as well as widespread components of pharmaceutical formulations. Therefore, development of highly sensitive, rapid, and economically efficient methods for the determination of catecholamines is of great interest. The spectroscopic analytical methods have a good potential in this respect. This mini-review summarizes in a concise manner some advances and trends in the determination of catecholamines by spectroscopic methods, including spectrophotometry, fluorescence spectroscopy, immunoassays with spectroscopic detection, Raman spectroscopy, and other methods. Information on mainly determined compounds and analyzed samples is given and discussed. Analytical strategies and performance for the quantitation of catecholamines in various samples are described.     

Graphane Nanostripes

Graphane, the hydrogenated counterpart of graphene, was shown to exhibit properties such as tunable band gaps through varied degrees of hydrogenation, fluorescence, or ferromagnetism. Graphane nanostripe properties have also been theoretically predicted. Herein, we show that graphane nanostripes can be prepared by opening carbon nanotubes using Birch reduction in liquid ammonia utilizing potassium as a reducing agent and water as a proton donor. The prepared graphane nanostripes exhibit several exceptional properties when coupled with trace metal dopants. The interplay of metallic nanoparticles and defects lead to a spin polarization and induction of ferromagnetic moment, as well as to enhanced electrocatalytic properties in the hydrogen evolution reaction when compared to non‐hydrogenated carbon nanotubes.     

Interaction of oligonucleotides with benzo[c]phenanthridine alkaloid sanguilutine

Benzo[c]phenanthridine alkaloid sanguilutine was extracted and purified from the dried roots of Sanguinaria canadensis. The interaction of the positively charged iminium form of alkaloid with double-stranded DNA oligonucleotides was studied using luminescence spectroscopy. The results showed that the interaction with various double-stranded oligonucleotides was not specific to A-T or G-C base pairs; also, no preference was found for either homogeneous or heterogeneous base composition of strands. The association constants were calculated to be in the range of (1.31–14.36) × 10⁵ M^?1. The luminescence intensity response at 610 nm to low concentrations of double-stranded DNA was found to be linear and can potentially be used for the fluorometric quantification of DNA. The limit of detection was estimated to be 120 ng mL^?1 of DNA (calculated by 3σ method).     

Supercapacitors in Motion: Autonomous Microswimmers for Natural‐Resource Recovery

An electroadsorption technique similar to the ultrafast charging mechanism in supercapacitors is utilized to remove metals with different sizes and hydrophilicities from contaminated water using self‐propelled microswimmers. The swimmers carry graphite fibre or bismuth with a layered crystal structure providing high electrostatic double‐layer capacitances. Unlike previous methods, this electrochemical technique does not only utilize the surface of the swimmers, but due to the interlayer spacing of the graphite and bismuth, it is able to store metals in ≈400 layers, allowing removal and recovery of >50 ppm lithium in only 5 min. A larger interlayer distance between bismuth sheets allows the removal of bigger cations (sodium and calcium), expanding the application of this method to a large variety of natural elements. Finally, magnetic navigation of charged swimmers to an oxygen‐saturated media causes oxidation and thus immediate release of the metal ions from the swimmers.     

Molybdenum HDS catalysts supported on niobia-silica

The effect of the amount of Nb₂O₅on the dispersion and reductive properties of Mo/Nb₂O₅-SiO₂ catalysts has been studied. Addition of niobium leads to an increase of the dispersion, and the reducibility of molybdenum. A synergetic effect of niobium on the catalytic activity in hydrodesulfurization of thiophene was observed at 5.4 wt.% of Nb₂O₅. This revised version was published online in June 2006 with corrections to the Cover Date.