Monitoring enzymic peroxidation of NAD by capillary electrophoresis

NAD⁺ is degraded by horse liver alcohol dehydrogenase in a reaction with p-methylbenzyl hydroperoxide, which acts as a pseudo-substrate. An unstable intermediate product (called compound I) is formed, and this is converted into the final product NADX. The reaction can be monitored by capillary electrophoresis. NADX migrates as two well resolved peaks (NADX₁ and NADX₂), which belong probably to the tautomers of the same substance. The intermediate product, compound I, has the same effective mobility as the conformer NADX₂ and it was impossible to separate compound I from NADX₂. The spectra taken during the separation show clearly that the “9-min” peak contains different compounds during the course of the reaction and the NADX₂ is not identical with compound I.     

Reagents for Detection of Carboxylate Anion Ligands after Chromatographic Separation of Zinc Carboxylato Complexes

JPC – Journal of Planar Chromatography – Modern TLC - Reagents for detection of carboxylate anions as components of zinc carboxylato mixed-ligand complexes, after chromatographic...     

Synthesis,biological and physicochemical properties of Zinc(II) salicylate and 5-chlorosalicylate complexes with theophylline and urea

New zinc(II) salicylate complex compounds of general formula (X-C₆H₃-2-(OH)COO)₂Zn · L_n · xH₂O (where X = H, 5-Cl; L = theophylline, urea; n = 2, 4; x = 1, 2, 4) were prepared and their thermal, spectral and biological properties were studied. It was found that the thermal decomposition of hydrated compounds starts with the release of water. During the thermal decomposition of anhydrous compounds, the release of salicylic acid, theophylline, urea, CO₂, H₂O and C₆H₅Cl takes place. Zinc oxide was found as the final product of the thermal decomposition heated up to 900 °C. The complexes were tested against bacteria, yeasts and filamentous fungi. The highest biological activity show 5-chlorosalicylate compounds.     

Preparative production and separation of 2-acetamido-2-deoxymannopyranoside-containing saccharides using borate-saturated polyolic exclusion gels

A new separation method based on the combination of exclusion and ion exchange chromatography in borate buffer was developed. It allows semi-preparatory and preparatory separation of isobaric N-acylhexosamines (C-2 epimers) and corresponding methyl glycosides (anomers and tautomers). Three types of polyolic gels were tested for these separations. Ion-exchange HPLC was used as a rapid and reliable method for the quantification of the respective analytes. NMR studies of the interactions of N-acetylhexosamines with borate confirmed the importance of a proper stereochemical arrangement of acetamido sugars for their interactions with borate anions.     

Comparison of the evaporation processes of classical spectrography and optical spectrometry tandem technique for the determination of the relevant environmental elements

The evaporation as a part of the spectrochemical excitation process is a complicated procedure during which different thermo-chemical reactions connected mainly to the formation of carbides are overshot. This one is accelerated namely at the 4000 K on the top of the carrier electrode. The carbide creation markedly affects the evaporation process of single elements of the given matrix and modifies this process. In spite of this it is evident that the intensity of the DC arc has a significant impact on the evaporation of all elements. The evaporation capability of two optical methods, the classical non-controlled direct current (DC) arc spectrography and the PC controlled DC arc optical emission spectrometry, have been compared for the determination of some environmental important elements (Al, Cr, Ni, and V). The experiments were carried out using grating spectrograph PGS-2 and simultaneous multi-channel LECO 750 spectrometer which is connected to a separated evaporation cell and adjusted to the Marinković plasma source. Standardized evaporation curves were designed and the half-time (t_50%) values and the total (t_100%) evaporation time values were calculated. The basic statistical evaluation was done and the main figures of the merit were calculated.     

Parameters influencing the electrodeposition of a Ni-Cu coating on Fe powders. II. Effect of particle size fraction,suspension density and rotation speed

The composition of a two-component Ni-Cu coating and the efficiency of its electrochemical deposition on Fe powder was studied by constant current electrolysis. A fluidized bed arrangement was applied. The variable parameters were: the particle size fraction, the density of the suspension of the Fe powder in the plating bath, and the intensity of the stirring of the fluidized bed. Both the Cu and Ni contents in the deposit decrease with increase in the particle size, and with decrease in the suspension density. Thus, the surface area available for the electrochemical process proved to be of high importance. Another important factor is the quality of the contacts of the powder particles with the current carrying compact electrode during which the deposition of Ni is preferred. This influence is manifested in a decrease of the Ni-Cu ratio in the deposit with an increase in the particle size and rotation speed and, consequently, with a decrease in the suspension density. The current efficiency values on the powder for optimum conditions reached 80%.     

Preparation,spectral, thermal,and biological properties of zinc(II) 4-chloro- and 5-chlorosalicylate complexes with methyl 3-pyridylcarbamate and phenazone

New zinc(II) 4-chloro- and 5-chlorosalicylate complex compounds of the general formula ((4- or 5-Cl)C₆H₃(2-OH)COO)₂Zn · L _n (where L = methyl 3-pyridylcarbamate, phenazone; n = 2, 4) were prepared and characterized by elemental analysis, thermal analysis (TG/DTG, DTA), and IR spectroscopy. During thermal decomposition, mpc, phen, chlorosalicylic acid, chlorophenol, carbon dioxide, and carbon monoxide were released. Volatile products of the thermal decomposition were confirmed by mass spectrometry. The final solid product of the thermal decomposition up to 700°C was zinc oxide or metallic zinc. Antimicrobial activity of the compounds prepared was tested against various strains of bacteria, yeasts and filamentous fungi. The highest antimicrobial effect was determined against the G⁺ bacteria S. aureus.     

Hydrophilic polycarbonate for generation of oil in water emulsions in microfluidic devices

This report details the method for rendering hydrophilic surfaces of microchannels fabricated in polycarbonate (PC). We characterize the wetting properties and stability of the hydrophilic character of two coatings--one formed by a layer of poly(allylamine) (PAH*) and the second including an additional layer of poly(styrene-sulfonate) (PSS). This second (PC-PAH/PSS) coating yields highly hydrophilic surface that is stable against weeks of exposure to various fluids including organic oils. This coating allows for stable generation of oil-in-water emulsions of hydrocarbon, silicone and fluorinated oils without the use of surfactants and over days of continuous use.     

Mass spectrometric profiling of N-linked oligosaccharides and uncommon glycoform in mouse serum with head and neck tumor

N-linked oligosaccharides obtained from total serum of mice with implanted head and neck tumors were analyzed and compared with those from control samples of healthy mice. Methods used include a combination of a derivatization procedure with phenylhydrazine (PHN) and analysis by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). Oligosaccharides were enzymatically released from total serum with PNGaseF and purified by high-performance liquid chromatography (HPLC) on a reversed-phase column. Mass spectra contained ion peaks of labeled oligosaccharides and MS/MS experiments provided useful data for the structural elucidation of these compounds. More than 40 N-glycans with compositions characteristic of high-mannose, hybrid, complex, neutral, and sialylated structures were identified in the serum of tumoral mice. Significant differences between samples were observed with respect to the abundances of high mannose and hybrid glycans. These oligosaccharides showed higher relative intensities in the spectra obtained from the cancer sera. Complex sialylated oligosaccharides had similar abundances in both types of sera, with the exception of fucosylated biantennary disialylated oligosaccharide, which was mostly detected with lower abundance in control samples. In the MALDI spectra, several minor species corresponded to uncommon carbohydrates. These structures have been investigated in detail by MS/MS. Among these novel glycoforms, a few sialylated oligosaccharides without a free reducing end were identified. Also, glycans with an extra 60 u were observed and likely feature the presence of a 2-acetamido-2-deoxyoctose residue attached on antennae of 3- or 6-linked mannose.