LIGHT-INDUCIBLE ABSORBANCE CHANGES AND VANADATE-SENSITIVE ATPase ACTIVITY ASSOCIATED WITH THE PRESUMPTIVE PLASMA MEMBRANE FRACTION FROM CAULIFLOWER INFLORESCENCES

Sucrose density gradient centrifugation of a microsomal membrane fraction of cauliflower inflorescences showed a strong correlation between a blue light mediated cytochrome b reduction (LIAC) and an ion stimulated nitrate-insensitive but a vanadate-sensitive ATPase activity at 38-40% sucrose. LIAC activity and vanadate-sensitive ATPase might be assigned to the same type of membrane different from ER, Golgi, tonoplast and mitochondria. The Mg²⁺-dependent ATP-hydrolytic activity obtained after purification of the microsomal fraction on an aqueous polymer two phase system was partially characterized. Temperature optimum (40°C), pH optimum (pH 7.0), vanadate inhibition (I₅₀ at 20 μ M ), substrate kinetics ( K _m= 1.37 m M Mg.ATP) and inhibitor studies all point to the presence of the frequently described plasma membrane ATPase. Potassium and Na⁺ stimulated the enzyme activity (20-40%). In general our data arc strongly in favour of the hypothesis that LIAC activity is localized on the plant plasma membrane. The cytochrome b involved in the light reaction has a midpoint potential near +150 mV. This cytochrome which has been previously shown in a cauliflower microsomal fraction is a constituent of the plasma membrane.     

The role of small silver clusters in photography

Size-selected silver cluster ions have been produced in a mass spectrometer arrangement and have been deposited onto binder-free AgBr microcrystals. Clusters containing less than four silver atoms did not catalyze development (reduction) of the microcrystals. However, application of clusters containing four or more silver atoms rendered the crystals immediately developable in a conventional photographic developer. This for the first time proves directly, that a so-called latent image speck under these conditions of development requires a minimum number of four silver atoms.     

Thermische Zersetzung von CuInSe2, LiInSe2 und LiInTe2

The thermal decompositions of CuInSe₂, LiInSe₂ and LiInTe₂ in vacuum at high temperatures were studied by using TG/DTG coupled with mass spectrometry. For CuInSe₂, two steps were found to be significant. Up to 1000 °C Se₂ and In₂Se evaporate, followed later by Cu₂Se. The Li-containing compounds show similar behaviour. However, Li⁺ was already detected during the first step. Obviously, Li₂Se dissociates more readily than Cu₂Se. No Cu⁺ species were detected up to the complete evaporation of CuInSe₂.     

Stereochemistry of planarchiral compounds,part X

2,7-Dibromo-1,6-methano[10]anulene (3) and 2,9-Dibromo-syn-1,6:8,13-diimino[14]anulene (9) were quantitatively separated into their enantiomers by chromatography on triacetylcellulose (TAC) in ethanol. X-ray structure analysis (Bijvoet technique) established the chiralities (+)(R)-3 and (+)(S)-9 for the dextrorotatory enantiomers.Comparison of the CD spectra allowed the configurational assignment to further optically active [10] and [14] anulenes which were also accessible by chromatography onTAC. Conversion of (+)(R)-2-bromo-1,6-methano[10]anulene (2) into the corresponding methylester (–)-4 confirmed its previously proposed chirality (–)(R).2,7-Dibromo-1,6-oxido[10]anulene (7) and 2,9-dibromo-syn-diimino[14]anulene (9) are in contrast to the 2,9-dibromo-syn-dioxido[14]anulene (10) optically stable until 250°C. Consequently their inversion barriers are higher than 42 kcal (176 kJ) mol^–1.The CD spectra of mono and disubstituted anulenes (with C₁ and C₂ symmetry, resp.) are compared: For the [10]anulenes theCotton effect around 330 nm seems to be specific for their configuration with a positive effect indicating (S)-chirality and vice versa. Some regularities concerning the chromatographic resolutions are discussed.

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Stereochemie planar chialer Verbindungen, 10. Mitt.: Röntgenkristallstruktur und absolute Chiralität überbrückter [10]- und [14] Anulene

Zusammenfassung 2,7-Dibrom-1,6-methano[10]anulen (3) und 2,9-Dibrom-syn-1,6:8,13-diimino[14]anulen (9) wurden durch Chromatographie an Triacetylcellulose (TAC) in Ethanol quantitativ in ihre Enantiomeren getrennt. Röntgenstruktur-analyse (Bijvoet-Technik) bewies für die rechtsdrehenden Enantiomeren die Chiralität (+)(R)-3 bzw. (+)(S)-9.Ein Vergleich der CD-Spektren ermöglichte die Konfigurationszuordnung weiterer optisch aktiver [10]- und [14]Anulene, die gleichfalls durch Chromato-graphie anTAC erhalten worden waren. Umwandlung von (+)(R)-2-Brom-1,6-methano[10]anulen (2) in den entsprechenden Methylester (–)-4 bestätigte dessen schon früher vorgeschlagene Chiralität (–)(R).Dibrom-1,6-oxido[10]anulen (7) und Dibrom-diimino[14]anulen (9) sind im Gegensatz zum Dioxido[14]anulen (10) bis 250°C optisch stabil. Ihre Inver-sionsbarrieren liegen somit über 42 kcal (176kJ) mol^–1.Die CD-Spektren von mono- und disubstituierten Anulenen (mit C₁ bzw. C₂-Symmetrie) werden verglichen: Für die [10]Anulene scheint derCottoneffekt um 330 nm konfigurationsspezifisch zu sein, wobei ein positiver Effekt (S)-Chiralität anzeigt — und vice versa. Einige Regelmäßigkeiten bezüglich der chromatographischen Enantiomerentrennung werden diskutiert.

     

The effect of gamma radiation on biodegradability of morpholine in aqueous solution

The effect of -radiation on the aqueous solution of morpholine was studied on the basis of UV spectrum measurement, COD /chemical oxygen demand/, TOC /total organic carbon/ and STOD /short-term oxygen demand/ determination and Pitter's kinetic test of biodegradation. The biodegradability of the model solution after irradiation became substantially worse.     

Dynamic processes in polymeric networks as studied by NMR relaxation methods

By means of NMR pulse methods molecular motions of polymer subchains in crosslinked polystyrene gels are studied. The temperature dependence of the effective transverse relaxation timeT _{2 eff} is explained by a local reorientation process. The local configuration of the elastic chains of the network is shown to be mainly determined by polymer-solvent interaction. The results are compared with those of concentrated solutions. The influence of static-like contributions to the 2nd moments is discussed.     

Magnetic and spectral properties of the coligand isomer pair: Cu{N(CN)2}2(pyrazole)2 and Cu{pyrazole · N(CN)2}2

Summary New coligand isomers of composition Cu{N(CN)₂}₂(pz)₂ and Cu{pz · N(CN)₂}₂ (pz = pyrazole) were prepared and studied by measuring their magnetic susceptibilities up to 4.2K and by aid of their e.s.r., ligand field and i.r. spectra. The susceptibility data have been analysed with various models for the exchange-coupled copper(II) polymers. It is shown that the resultant exchange coupling is ferromagnetic for Cu{N(CN)₂}₂(pz)₂ (J 1.1 - 1.4 cm^–1) but antiferromagnetic for Cu{pz · N(CN)₂}₂ (J –0.4 cm^–1). A polymeric chain structure is proposed for Cu{N(CN)₂}₂(pz)₂ havingpseudo-octahedrally coordinated copper(II) and CN-bridging dicyanamide ligands. Its coligand isomer contains anionic chelate ligands, formed by nucleophilic addition between N(CN)₂ and pz in the copper(II) coordination sphere, and giving with this central atom a square-planar system. Definite, but slight axial interaction takes place between these structure units.     

Photobleaching of radiation induced trapped electrons in neutral and alkaline glasses. Hydrogen atom formation

Photomobilization of trapped electrons in 7 M NaClO₄- and 9 M NaOH-glass gives rise to trapped hydrogen atoms. This is probably due to the reaction e^?_m + H₂O → H + OH^?. Experiments with an electron scavenger indicate that electrons are not precursors to radiolytically produced hydrogen atoms. It seems that the mobile electrons produced during photobleaching are not slowed down to thermal energy before they react to produce hydrogen atoms, since the yield of the latter species is strongly dependent on the wavelength of the bleaching light.     

Hydrogen bond studies: Part 118. A deuteron magnetic resonance study of BeSO4· 4D2O and Li2SO4· D2O

The electric field gradient (EFG) tensors at the deuterons in the water molecules in BeSO₄ · 4D₂O at 25°C are reported. The quadrupole coupling constants (e²Q/h) and asymmetry parameters (η) for the two independent deuterons are 181.1(4) and 194.8(3) kHz, and 0.226(4) and 0.123(3), respectively. The EFG tensor corresponding to the smallest e²qQ/h is considerably distorted by the beryllium ion, which causes a high η value as well as a deviation of the y-principal axis by 21.8(6)° from the normal to the water molecule plane. A redetermination of the EFG tensors at the deuterons in the water molecule in Li₂SO₄ · D₂O at 25°C and ?110°C is also reported. The e²Q/h and η values for the two deuterons are 236.6(1.2) and 239.8(1.1) kHz, and 0.091(8) and 0.126(7), respectively, at ?110°C. The corresponding e²qQ/h and η values for the averaged EFG tensor at 25°C are 125.8(1.1) kHz and 0.813(13), respectively. The results are in good agreement with those from the pioneer work by Ketudat and Pound, 20 years ago on the same compound.