Principle of a new immunoassay based on electrophoretic mobility of poly(styrene/alpha-tert-butoxy-omega-vinylbenzyl-polyglycidol) microspheres: application for the determination of helicobacter pylori IgG in blood serum

The principle of a novel latex diagnostic test for the determination of antibodies against Helicobacter pylori in blood sera is described. The test is based on the measurement of the electrophoretic mobility of the microspheres with immobilized H. pylori antigens. The electrophoretic mobility of these microspheres depends on the concentration of the antibodies against H. pylori in suspending medium. Particles with hydrophilic polyglycidol in the surface layer were used for the test. The microspheres were obtained by an emulsifier-free emulsion copolymerization of styrene and alpha-tert-butoxy-omega-vinylbenzyl-polyglycidol macromonomer (D(n) = 220 nm, diameter polydispersity factor D(w)//D(n) = 1.02). Activation of polyglycidol hydroxyl groups with cyanuric chloride allowed for covalent immobilization of H. pylori antigens. The fraction of H. pylori not specifically adsorbed onto the microspheres was negligible. Changes of the electrophoretic mobility of the microspheres with the surface concentration of the covalently immobilized H. pylori antigens Gamma = (1.6 +/- 0.3) . 10(-3) g m(-2) were suitable for the detection of the antibodies in the sera of patients with titer in the range (determined by the indirect ELISA test) from 1:500 to 1:32 000.     

PEG‐dialdehyde–the new cross‐linking agent for collagen/elastin hydrogels

Collagen and elastin are the major proteins of an extracellular matrix. They possess attractive, complementary mechanical properties in their native state, but during isolation, its unique structure is destroyed, which affects the parameters of the materials. However, they still have excellent biological properties. The cross‐linking process improves the physicochemical properties of protein materials. The ideal cross‐linking agent should be effective and does not impair the biological properties of the material. Therefore, poly(ethylene) glycol‐dialdehyde was used in the study. The results show that the addition of poly(ethylene) glycol‐dialdehyde in combination with the neutralization of a collagen/elastin solution is a useful method for preparation of protein hydrogels. The gels are transparent and relatively stiff. They exhibit good mechanical properties, surface properties and are attractive for 3 T3 cells. Copyright © 2016 John Wiley & Sons, Ltd.     

Kinetics and mechanism of H+(aq)-assisted aquation of [Cr(N3)(S-pdtra)]− and [Cr(N3(edtrp)]−ions

Two new complex anions, [Cr(N3)(S-pdtra)]– and [Cr(N3)(edtrp)]–, were obtained in solution by N3–/HN3 anation of the aqua analogues (S-pdtra = S-propane-1,2-diamine-N,N,N-triacetate, edtrp = ethylenediamine-N,N,N-tripropionate). Aquation of these species in acidic media leads to the same geometrical isomers as those used for the synthesis. The aquation rate is strongly dependent upon [H] and is substantially higher in D2O than in H2O. Protonation of the coordinated azide was not observed spectrophotometrically. The rate law and activation parameters have been determined and discussed.     

Identification of a novel high affinity copper binding site in the APP(145-155) fragment of amyloid precursor protein

The copper(II) binding features of the APP(145-155) and APP(145-157) fragments of the amyloid precursor protein, Ac-Glu-Thr-His-Leu-His-Trp-His-Thr-Val-Ala-Lys-NH2 and Ac-Glu-Thr-His-Leu-His-Trp-His-Thr-Val-Ala-Lys-Glu-Thr-NH2 were studied by NMR spectroscopy and NMR findings were supported by UV-vis, CD and EPR spectra. Potentiometric measurements were performed only for the more soluble Ac-Glu-Thr-His-Leu-His-Trp-His-Thr-Val-Ala-Lys-Glu-Thr-NH2 peptide fragment. The following was shown: (i) the imidazole rings of all the three His residues are involved in metal coordination; (ii) metal binding induces ionisation of Leu-148 and His-149 amide nitrogens that complete the donor set to copper(II) in the species dominant at neutral pH; (iii) the unusual coordination scheme of the His-Xxx-His-Xxx-His consensus sequence justifies the high specificity for Cu(II) when compared to SOD-like or albumin-like peptides or even in amyloid Abeta fragments. The present findings may represent the key for interpreting the observed requirement of His residues conservation for the redox cycling between Cu(II) and Cu(I) by soluble APP.     

Stearic acid spin labels in lipid bilayers: insight through atomistic simulations

Spin-labeled stearic acid species are commonly used for electron paramagnetic resonance (EPR) studies of cell membranes to investigate phase transitions, fluidity, and other physical properties. In this paper, we use large-scale molecular dynamics simulations to investigate the position and behavior of nitroxide spin labels attached to stearic acid molecules in dipalmitoylphosphatidylcholine (DPPC) bilayers. The results of these studies are potentially very important for the interpretation of EPR spectra, which rely on assumptions about the position of the label in the membrane. Additionally, we investigate the effect of chirality and ionization of the carboxyl group of the label. For a non-ionized species, we observe that spin-label molecules are even able to make flip-flop transitions between the leaflets of the bilayer. Such transitions have been previously observed only in very rare cases in molecular simulations.     

Studies on pyrazine derivatives LII: Antibacterial and antifungal activity of nitrogen heterocyclic compounds obtained by pyrazinamidrazone usage

Using reactivity of pyrazinamidrazones and their N′‐substituted derivatives 1–8 in reaction with sulfonyl chlorides sulfone derivatives 9–17 were obtained, with orthoformate cyclized to sulfonyl compounds 18–20 . Amidrazones in reaction with pyraziniminoesters gave dihydrazidines 21–23 , which cyclized to 3,5‐dipyrazine derivatives of 1,2,4‐triazole 24–26 . 1‐Methyl‐ or 1‐phenyl‐3‐pyrazine‐1,2,4‐triazole 27–38 was formed in reaction of amidrazones 1–8 with orthoformate and orthoacetate or benzoyl chloride. N′‐Phenylamidrazones 3, 8 in reaction with thionyl chloride were transformed to 1,2,3,5‐thiatriazole S‐oxides 39, 40 . Obtained compounds exhibited low antibacterial activity. Antifungal activity was affirmed for compounds 1, 3, 4, 5, 8, 37, 39, and 40 , for which minimal inhibitory concentration (MIC) was in the concentration range of 16–128 μg/mL. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 23:49–58, 2012; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20751