GD3- and O-acetylated GD3-gangliosides in the GM2 synthase-deficient mouse brain and their immunohistochemical localization

Gangliosides in the brain of the knockout mouse deficient in the activity of β1,4 N-acetylgalactosaminyl transferase (β1,4 GalNAc-T)(GM2 synthase) consisted of nearly exclusively of GM3- and GD3-gangliosides as expected from the known substrate specificity of the enzyme and in confirmation of the initial reports from two laboratories that generated the mutant mouse experimentally. The total molar amount of gangliosides was approximately 30% higher in the mutant mouse brain than that in the wild-type brain. However, contrary to the initial reports, one-fourth of total GD3-ganglioside was O-acetylated. It reacted positively with an anti-O-acetylated GD3 monoclonal antibody and disappeared with a corresponding increase in GD3-ganglioside after mild alkaline treatment. The absence of O-acetylated GD3 in the initial reports can be explained by the saponification step included in their analytical procedures. Although quantitatively much less and identification tentative, we also detected GT3 and O-acetylated GT3. Anti-GD3 and anti-O-acetylated GD3 monoclonal antibodies gave positive reactions in the brain of mutant mouse as expected from the analytical results. Either antibody barely stained wild-type brain except for immunoreactivity of GD3 in the cerebellar Purkinje cells. The distributions of GD3 and O-acetylated GD3 in the brain of mutant mouse were similar but differential localization was noted in the cerebellar Purkinje cells and cerebral cortex.     

Extraction of Palladium(II) and Platinum(IV) from Hydrochloric Acid Solutions with Trioctylammonium Nitrate Ionic Liquid without Dilution

The fundamental properties and extraction capability of an ionic liquid (IL), trioctylammonium nitrate ([HTOA][NO₃]), for Pd^II and Pt^IV, are investigated. At room temperature, [HTOA][NO₃] is a solid (melting point: 30.7 °C), but it becomes a liquid (melting point: 16.7 °C) when saturated with water. Water-saturated [HTOA][NO₃] exhibits a viscosity of 267.1 mPa·s and an aqueous solubility of 2.821?×?10^?4 mol·dm^?3 at 25 °C, and can be used as an extraction solvent without dilution. [HTOA][NO₃] exhibits an extremely high extraction capability for Pd^II and Pt^IV in dilute hydrochloric acid (0.1–2 mol·dm^?3 HCl); the distribution ratio reaches 3 × 10⁴ for both the metals. From electrospray ionization mass spectrometry analysis, the species extracted in the IL phase are [PdCl₃]^? and [PdCl₂(NO₃)]^? for Pd^II and [PtCl₆]^2? and [PtCl₅]^? for Pt^IV. A majority of the other transition metals are considerably less or marginally extracted into [HTOA][NO₃] from a 0.1 mol·dm^?3 hydrochloric acid solution. The extraction capacity of [HTOA][NO₃] is greater than that of other hydrophobic ILs such as [HTOA]Cl and bis(trifluoromethanesulfonyl)imide-based ILs. The metals extracted into the IL phase are quantitatively back-extracted using an aqueous solution containing thiourea and nitric acid. By controlling the thiourea concentration and shaking time, Pd^II and Pt^IV are mutually separated to some extent in the back extraction process. The IL phase used for the back extraction can be reused for the forward extraction of these metals after scrubbing it with an aqueous nitric acid solution.     

Bemerkungen über Thermochromie von Kobalt(II) chloridlösungen in organischen Medien, 1. Mitt.: Lösungen in verschiedenen Alkoholen

The thermochromism of solutions of cobalt(II) chloride in methanol, ethanol, n- and iso-propyl, n-, iso- and sec. butyl alcohol was studied spectrophotometrically. The blue color of these solutions fades with decreasing temperature, solutions in primary alcohols being especially variable, becoming pink at sufficiently low temperature. Solutions in secondary alcohols are, on the other hand, much less variable. The thermochromism can be ascribed, in general, to the shift of the equilibrium $$[CoL_2 Cl_2 ] + (3 - 4) L\begin{array}{*{20}c} \to \\ \leftarrow \\ \end{array} ([CoL_5 Cl]^ + or [CoL_6 ]^{2 + } ) + (1 - 2) Cl^ - $$ (L: solvent molecule). In the case of methanol, however, the two equilibria $$[CoLCl_3 ]^ - + 4 L \begin{array}{*{20}c} \to \\ \leftarrow \\ \end{array} [CoL_5 Cl]^ + + 2 Cl^ - $$ and $$[CoL_5 Cl]^ + + L\begin{array}{*{20}c} \to \\ \leftarrow \\ \end{array} [CoL_6 ]^{2 + } ) + Cl^ - $$ seem to be shifted one after another. The significance of the difference between primary and secondary alcohols is briefly discussed in connection with some related effects, i.e. the pressure effect studied byKitamura andOsugi ⁷ and the water effect found byKato et al.¹⁰.     

Preparation and some spectral properties of benzo-fused 1,4-dimethyl-2(1H)-quinolinones

The preparation of the angular and linear isomers of benzo-fused 1,4-dimethyl-2(1H)-quinolinones 3a–5a and their spectral data including ¹³C-nmr data are reported. Structural difference among 3a–5a is confirmed from the proximity effect in ¹H- and ¹³C-nmr data and from the uv spectral pattern.     

Regulated interaction between polypeptide chain elongation factor-1 complex with the 26S proteasome during <Emphasis Type="Italic">Xenopus</Emphasis> oocyte maturation

Background  

During Xenopusoocyte maturation, the amount of a 48 kDa protein detected in the 26S proteasome fraction (p48) decreased markedly during oocyte maturation to the low levels seen in unfertilized eggs. The results indicate that the interaction of at least one protein with the 26S proteasome changes during oocyte maturation and early development. An alteration in proteasome function may be important for the regulation of developmental events, such as the rapid cell cycle, in the early embryo. In this study, we identified p48.     

Screening of Dowex® anion-exchange resins for invertase immobilization

Commercial yeast invertase (Bioinvert^®) was immobilized by adsorption on anion-exchange resins, collectively named Dowex^® (1×8:50–400, 1×4:50–400, and 1×2:100–400). Optimal binding was obtained at pH 5.5 and 32°C. Among different polystyrene beads, the complex Dowex-1×4–200/invertase showed a yield coupling and an immobilization coefficient equal to 100%. The thermodynamic and kinetic parameters for sucrose hydrolysis for both soluble and insoluble enzyme were evaluated. The complex Dowex/invertase was stable without any desorption of enzyme from the support during the reaction, and it had thermodynamic parameters equal to the soluble form. The stability against pH presented by the soluble invertase was between 4.0 and 5.0, whereas for insoluble enzyme it was between 5.0 and 6.0. In both cases, the optimal pH values were found in the range of the stability interval. The K _m and V _max for the immobilized invertase were 38.2 mM and 0.0489 U/mL, and for the soluble enzyme were 40.3 mM and 0.0320 U/mL.     

Synthesis of isocorrole and the higher homologues

Bis(azafulvene) derivative of gem-dimethyldipyrrylmethane reacted with 2,2′-bipyrrole under neutral conditions without catalyst to give a mixture of expanded isocorroles in ca. 50% total yields. GPC separation gave eleven porphyrinoids containing 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, and 44 units of pyrrole.     

Adsorption, Migration and Reactions of Hydrocarbons on Zeolites Observed by Ftir Spectroscopy

The adsorption, migration and reactions of hydrocarbons on zeolites studied by FTIR spectroscopy are briefly reviewed. At low temperatures, alkyl-BAS (Brønsted acid sites) and -BAS complexes were first formed before protonation of olefins. For 1-butene, it underwent double bond migration (DBM) to form cis- and trans-2-butenes. With increasing temperature, oligomerization occurred and resulted in highly branched dimer, e.g., 3,4-dimethyl-3-hexene. Compared with 1-butene, isobutene can oligomerize at much lower temperature and formed dimerized alkoxy species, even on isolated silanols of zeolites. Upon adsorption of cyclic olefins such as 1-methylcyclopentene, alkenyl carbenium ions were formed at temperatures as low as 150 K. The adsorption of butenes on ferrierite indicates the existence of energy barriers for their intercalation into the pores. The H/D isotope exchange reaction of alkanes with acidic hydroxyl groups of zeolites will also be discussed.     

Characterization of Cu species on SiO2 and ZSM-5 by temperature-programmed reduction by ammonia

We studied the temperature-programmed reduction by NH₃ (NH₃-TPR) as a supplement to the temperature-programmed reduction by H₂ (H₂-TPR) for the characterization of supported Cu species. The NH₃-TPR profile of Cu/SiO₂, which contained only bulk CuO, exhibited two peaks for N₂ formation in equal amounts, suggesting stepwise reduction of the bulk CuO. In contrast, the H₂-TPR profile exhibited only one H₂ consumption peak. We also studied Cu-NaZSM-5 samples with various Cu and Na loadings. The Cu ions on ZSM-5 were reduced to Cu⁺ but no further. Kinetic analysis revealed that the NH₃-TPR profile exhibited peaks for separate reductions of isolated and binuclear Cu²⁺ ions. Thus, we found NH₃-TPR to be useful for detailed analysis of the reducibility of Cu²⁺ to Cu⁺ in zeolite pores.