Single channel recordings of alpha-hemolysin reconstituted in S-layer-supported lipid bilayers.

Previous studies demonstrated that lipid membranes attached to a proteinaceous crystalline surface-layer (S-layer) revealed a prolonged lifetime and showed a reduced tendency to rupture in the presence of membrane active molecules. In addition, comparative studies on folded and S-layer-supported lipid membranes (SsLM) revealed an uniform capacitance of 0.64 +/- 0.04 microF/cm(2) for both composite membranes. In the present study, the feasibility to reconstitute the channel-forming protein alpha-hemolysin (alpha HL) into SsLM at single channel resolution was investigated. Single alpha HL channels could be recorded and the intrinsic properties like unitary conductance, current-voltage characteristics, and closure was found to be similar at both membranes. Thus, the tightly attached S-layer allowed complete reconstitution of alpha HL channels in SsLM.     

Temperature-dependent surface X-ray diffraction on K/Ag(001)-(2 × 1)

Temperature-dependent surface X-ray diffraction experiments have been performed on the K/Ag(001)-(2 × 1) adsorption system. The structure is characterized by a missing-row geometry in which alternate Ag rows along [1 0] are missing. The K atoms reside within the large grooves coordinated by six Ag atoms at a distance of 3.44(5) Å, corresponding to an effective K-radius of 2.00(5) Å. Large anisotropic disorder is observed for both the K-atoms and the top-layer (“ridge”) Ag atoms. The K-atom displacements are largest in the direction along the grooves, whereas for the Ag atoms the vibrations along [110] are significantly larger. The temperature dependence of the Ag vibrations is in accordance with Debye theory for the [110] direction, but deviates from it for the [1 0] vibrations at high temperature. In contrast to the K-atoms, the out-of-plane vibrations of the top-layer Ag atoms are larger than the in-plane vibrations. The inclusion of anharmonic contributions to describe the Ag disorder significantly improves the fits. It is shown that if anharmonicity is neglected the interlayer contraction is overestimated (Δd₁₂/d₁₂ only −3.2%, instead of −12.7% if anharmonicity is neglected). Due to the anharmonicity, different definitions of the atomic position arise (mean, mode and equilibrium position), which are discussed on the basis of the results.     

Ternäre Verbindungen des Lithiums und Natriums mit Mangan und Elementen der 5. Hauptgruppe

Es wird über Darstellung und Kristallstruktur ternärer AMnX-Verbindungen (A ? Li, Na; X ? P, As, Sb, Bi) berichtet. Sie kristallisieren tetragonal in Raumgruppe P4/nmm-D_4h⁷, wobei sich LiMnX und NaMnX durch unterschiedliche Punktlagen der Alkaliatome unterscheiden. Die AMnX-Strukturen werden mit denen verwandter AMX-Verbindungen verglichen (A ? Li, Na, K, Rb; M ? Be, Mg, Zn, Cd; X ? 5b-Element). Ternary Compounds of Lithium and Sodium with Manganese and Elements of the Fifth Main Group Formation and crystal structure of ternary AMnX compounds (A ? Li, Na; X ? P, As, Sb, Bi) are reported. These compounds crystallize in the tetragonal space group P4/nmm-D. The structures of LiMnX and NaMnX differ by the positions of the alkali atoms. Structural relationship to AMX compounds (A ? Li, Na, K, Rb; M ? Be, Mg, Zn, Cd; X ? 5b element) are discussed.     

The cope rearrangement in substituted semibullvalenes as studied by dynamic 13C NMR

NMR-data for some substituted semibullvalenes are reported and the Cope rearrangement is analysed kinetically. Substituent effects on the activation barriers are discussed.     

Neue ternäre Phasen von Platinmetallen mit Lithium und Elementen der 4. Hauptgruppe

Novel Ternary Phases of Platinum Metals with Lithium and Main Group IV Elements The elements palladium, platinum, and iridium (Me) form ternary compounds with lithium and the elements germanium, tin or lead (X) of the formulas Li₂MeX and/or LiMe₂X. The lattice constants of the cubic fc. crystallizing compounds see ?Inhaltsübersicht”?. Besides the cubic form of LiPd₂Ge there exists a tetragonal structure with a = 6.25₄ and c = 6.41₀ Å. X-ray investigations on single crystals showed that LiPd₂Ge crystallizes in a Heusler lattice (L2₁A type), Li₂PdSn has a modified Li₃Bi structure (L2₁C type). The homogeneity range between the compositions Li₂PdX and LiPd₂X was investigated.     

Deuteriumoxid-Wasser-Misehungen

Ohne Zusammenfassung