Reactions of free radicals with monoethyldichlorochromium(III) tris(tetrahydrofuranate)

σ-Ethyl-chromium(III)dichloride · 3 THF reacts with free radicals by formation of a transient paramagnetic complex which decomposes giving the combination product of alkyl ligand and radical.     

Ueber Entstehung von Liesegang'schen Ringen bei der serologischen Präzipitation

Ohne Zusammenfassung     

Electrochemical insertion of lithium in mechanochemically synthesized Zn2SnO4

We studied the electrochemical insertion of Li in mechanochemically prepared Zn(2)SnO(4). The mechanism of the electrochemical reaction was investigated by using X-ray diffraction, nuclear magnetic resonance spectroscopy, and M?ssbauer spectroscopy. Changes in the morphology of the Zn(2)SnO(4) particles were studied by in situ scanning electron microscopy. The results were compared with mixtures of SnO(2) + ZnO and with Zn(2)SnO(4) prepared by conventional solid-state synthesis and showed that the mechanochemically prepared Zn(2)SnO(4) exhibits the best cyclic stability of these samples.     

Rhodopsin Activation Switches in a Native Membrane Environment†

The elucidation of structure–function relationships of membrane proteins still poses a considerable challenge due to the sometimes profound influence of the lipid bilayer on the functional properties of the protein. The visual pigment rhodopsin is a prototype of the family of G protein‐coupled transmembrane receptors and a considerable part of our knowledge on its activation mechanisms has been derived from studies on detergent‐solubilized proteins. This includes in particular the events associated with the conformational transitions of the receptor from the still inactive Meta I to the Meta II photoproduct states, which are involved in signaling. These events involve disruption of an internal salt bridge of the retinal protonated Schiff base, movement of helices and proton uptake from the solvent by the conserved cytoplasmic E(D)RY network around Glu134. As the equilibria associated with these events are considerably altered by the detergent environment, we set out to investigate these equilibria in the native membrane environment and to develop a coherent thermodynamic model of these activating steps using UV–visible and Fourier‐transform infrared spectroscopy as complementary techniques. Particular emphasis is put on the role of protonation of Glu134 from the solvent, which is a thermodynamic prerequisite for full receptor activation in membranes, but not in detergent. In view of the conservation of this carboxylate group in family A G protein‐coupled receptors, it may also play a similar role in the activation of other family members.