Rapid imaging, using a cooled charge-coupled-device, of fluorescent two-dimensional polyacrylamide gels produced by labelling proteins in the first-dimensional isoelectric focusing gel with the fluorophore 2-methoxy-2,4-diphenyl-3(2H)furanone

A new method for visualising proteins in two-dimensional polyacrylamide gels was developed. Proteins were labelled with the fluorophore 2-methoxy-2,4-diphenyl-3(2H)furanone (MDPF) while present in the first-dimensional gel after isoelectric focusing and subsequently electrophoresed into the second-dimensional gel. High resolution spot patterns were produced and compared with other methods of visualisation. A new rapid imaging system based on a cooled charge-coupled-device was used to view the two-dimensional fluorescent protein spot patterns. The method allows the immediate and rapid imaging of two-dimensional gels at the end of electrophoresis with no further processing.     

Thermal degradation of copolymers of methyl methacrylate and methyl acrylate. I. Products and general characteristics of the reaction

The technique of thermal volatilization analysis (TVA), applied to methyl methacrylate–methyl acrylate copolymers having molar composition ratios 112/1, 26/1, 7.7/1, and 2/1, has demonstrated that the stabilization of poly(methyl methacrylate) by copolymerized methyl acrylate is due to inhibition of the depolymerization initiated at terminally unsaturated structures, probably by direct blockage by methyl acrylate units. The molecular weight of the copolymers decreases rapidly during degradation, suggesting that a random scission process is involved. The products of degradation consist of the monomers, carbon dioxide, chain fragments larger than monomer, and a permanent gas fraction which is principally hydrogen. Infrared and ultraviolet spectral measurements suggest that the residual polymer, which is colored, incorporates carbon–carbon unsaturation. The complete absence of methanol among the products is surprising in view of its abundance among the products of degradation of poly(methyl acrylate). These observations have been accounted for qualitatively in terms of acceptable polymer behavior.     

Flow injection-spectrophotometric determination of cresol compounds in water by reaction withp-aminophenol

A spectrophotometric method has been developed for the simultaneous determination ofo-cresol andm-cresol in water by reaction withp-aminophenol (PAP). Three different methodologies have been assayed; (i) batch analysis, after reaction in an alkaline medium in the presence of dissolved molecular oxygen as oxidizing agent, (ii) a stopped-flow procedure, carried out in the presence of KIO₄ and (iii) a flow injection method based on the same approach. The batch procedure requires 22 min for the full development of colour witho-cresol and 12 min form-cresol. In the stopped-flow mode, using KIO₄ and a reaction time of 12 min, better sensitivity can be obtained for both compounds and limits of detection of 10 g 1^–1 foro-cresol and 30 g 1^–1 form-cresol were found. The flow injection method has a lower sensitivity but permits more than 80 injections per hour. Based on the different maximum absorbance wavelengths obtained for the reaction products of PAP witho-cresol (614 nm) andm-cresol (632 nm), both compounds can be simultaneously determined in water samples and recoveries of 90 to 115% were found in spiked water samples of different types.     

Porphyrins. 35. Unusual course of the Vilsmeirr reaction when formylating the platinum complex of octaethylporphyrin (revision of the known reaction)

The formation of complexes of -formyl-heptaethylporphyrin and -(2-formylvinyl)-heptaethylporphyrin in addition to the expected mesoformylporphyrin was detected when formylating the platinum complex of actaethylporphyrin by the Wilsmeier reaction. A possible mechanism is proposed for the unusual formation of similar compounds.Institute of Biomedicinal Chemistry, Russian Academy of Medical Sciences, Moscow 119832. Translated from Khimiya Geterotskilicheskikh Soedinenii, No. 3, pp. 324–328, March, 1997.     

Monte Carlo study of the aqueous hydration of dimethylphosphate conformations

Monte Carlo computer simulations were performed on dilute aqueous solutions of the dimethylphosphate anion and the sodium dimethylphosphate ion pair, with the two phosphodiester torsional angles in the gauche–gauche, gauche–trans, and trans–trans conformations. The structural and energetic aspects of the aqueous hydration of each molecule were analyzed in terms of quasi component distribution functions based on the proximity criterion and partitioned into ionic, hydrophilic, and hydrophobic contributions to facilitate an understanding of the hydration pattern and conformational trends in these multifunctional solutes. Special attention was also paid to methodological issues affecting hydration, such as statistical uncertainty in the determined hydration indices, choice of partial atomic charges for the solute atoms, and solute–water interaction potentials adopted in the simulations. The results showed that gauche–trans and gauche–gauche forms are equally favorable for the dimethylphosphate anion with the trans extended form destabilized by hydration. The sodium dimethylphosphate ion pair hydration energetically favors the trans–trans conformation.     

Theoretical investigation of 1,4-dioxane complexes with water in the <Emphasis Type="Italic">chair</Emphasis> conformation by semiempiric MNDO/PM3 method

The structure and relative stability of 1,4-dioxane-water, (Diox)_n·(H₂O )_m (n = 1, 2, m = 1–6), molecular complexes have been calculated by semiempirical MNDO/PM3 method. A considerable variety of (Diox)_n·(H₂O )_m isomeric structures was stated. The mean energy of O_Diox…H_W-O_W hydrogen bond in (Diox)_n·(H₂O)_m complexes formed by 1,4-dioxane molecules in the chair conformation amounts to ?2.293 ± 0.210 kcal/mol with the average bond length 2.797 0.015 Å.     

Hydroxy acids of the reserve lipids of Galeopsis bifida

The structures of fatty monohydroxy acids of the lipids of the seeds ofGaleopsis bifida Boenn. have been studied by the methods of chromatographic, spectral, and chemical analysis. (31) Acids with chain lengths of from 14 to 20 carbon atoms, with from 0 to 3 double bonds, and with the hydrolyls in positions characteristic for the products of the direct hydroxylation and the lipoxygenase and photosensitized oxidation of unsaturated fatty acids were detected. Of them, the 13-OH-9Z, 11E-17:2, the 15-OH-9, 12-18:2, the 16-OH-9, 12-18:2, and 17-OH-11, 14-20:2 acids were new, while this is the first time that the 15-OH-9Z, 12Z, 16E-18:3 acid has been described as a natural compound. The behavior of the TMS derivatives of the hydroxy acids on a polyester phase in GLC is discussed.Institute of the Chemistry of Plant Substances, Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 744–753, November–December, 1991.     

Synthesis and transformations of 4-hydroxy-5-methyl-2-trifluoromethylpyridine

4-Hydroxy-5-methyl-2-trifluoromethylpyridine was synthesized from 3-hydroxy-3-methyl-6-trifluoromethyl-2,3-dihydro-4H-pyran-4-one. Its methylation leads to the formation of a mixture of N- and O-alkylation products, which were isolated chromatographically in the pure state. Convenient methods of their preparation are proposed.Belorussian State University, Minsk 220050. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 780–784, June, 1998.     

Oxidation of α-pinene by OH•, Cl• and Cl2 •− radicals Error! Reference source not found

The rate constants of the reactions of the radicals OH^? and Cl₂ ^?? with α-pinene determined by pulse radiolysis in aqueous solution are given. The reaction of Cl^? with α-pinene has been studied by laser photolyis in CCl₄ solution. Furthermore, the rate constants of the reactions of the formed organic radicals with oxygen as well as those of the deactivation of all radicals were determined.