Light-emitting devices from the tris(2,2'-bipyridyl)ruthenium(II) complex [Ru(bpy)(3)(2+)] and new derivatives thereof were prepared. Due to the electrochemical nature of the device operation, single-layer devices in an ITO/ Ru(bpy)(3)(2+) complex + PMMA/Ag sandwich configuration achieved very high external quantum efficiencies. The derivatives of the Ru(bpy)(3)(2+) complex were designed and synthesized to inhibit self-quenching of the excited state by adding different alkyl substituents on the bipyridyl ligands. As a result, devices that contain these new Ru(bpy)(3)(2+) complexes show a higher photoluminescence and electroluminescence efficiency than devices made from the unmodified Ru(bpy)(3)(2+) complex. External quantum efficiencies up to 5.5% at brightnesses in the range of 10-50 cd/m(2) are reported. In addition, the response time of such devices (which is a result of the electrochemical operation) has been shortened dramatically. An "instantaneous" light emission is achieved for devices that employ smaller counterions such as BF(4)(-) to increase the ionic conductivity. Such a device shows a response time of less than 1 s to emit 10-20 cd/m(2) after the operating voltage of 2.4 V has been applied.

SummaryWe conducted a placebo-controlled, cross-over trial to examine the effect of Lactobacillus casei Shirota (LcS) on natural killer (NK) cell activity in humans. NK cell activity exhibited a declining trend during the period of placebo ingestion, but NK cell activity increased after intake for 3 weeks of fermented milk containing 4 × × × × 10 10 live LcS. When human peripheral blood mononuclear cells were cultured in the presence of heat-killed LcS, NK cell activity was enhanced. The ability of LcS to enhance NK cell activity and induce interleukin (IL)-12 production was correlated, and the addition of anti-IL-12 monoclonal antibody reduced the enhancement of NK cell activity triggered by LcS. In addition, separation of NK cells from LcS-stimulated monocytes with membrane filter reduced NK cell activity to the intermediate level and almost deprived monocytes of the ability to produce IL-12. These results demonstrate that LcS can enhance NK cell activity in vivo and in vitro in humans, and IL-12 may be responsible for enhancement of NK cell activity triggered by LcS.

Mitochondrial cytochrome c oxidase (CcO) transfers electrons from cytochrome c (Cyt.c) to O2 to generate H2O, a process coupled to proton pumping. To elucidate the mechanism of electron transfer, we determined the structure of the mammalian Cyt.c–CcO complex at 2.0‐Å resolution and identified an electron transfer pathway from Cyt.c to CcO. The specific interaction between Cyt.c and CcO is stabilized by a few electrostatic interactions between side chains within a small contact surface area. Between the two proteins are three water layers with a long inter‐molecular span, one of which lies between the other two layers without significant direct interaction with either protein. Cyt.c undergoes large structural fluctuations, using the interacting regions with CcO as a fulcrum. These features of the protein–protein interaction at the docking interface represent the first known example of a new class of protein–protein interaction, which we term “soft and specific”. This interaction is likely to contribute to the rapid association/dissociation of the Cyt.c–CcO complex, which facilitates the sequential supply of four electrons for the O2 reduction reaction.

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We developed a method, named GraDeR, which substantially improves the preparation of membrane protein complexes for structure determination by single-particle cryo-electron microscopy (cryo-EM). In GraDeR, glycerol gradient centrifugation is used for the mild removal of free detergent monomers and micelles from lauryl maltose-neopentyl glycol detergent stabilized membrane complexes, resulting in monodisperse and stable complexes to which standard processes for water-soluble complexes can be applied. We demonstrate the applicability of the method on three different membrane complexes, including the mammalian FoF1 ATP synthase. For this highly dynamic and fragile rotary motor, we show that GraDeR allows visualizing the asymmetry of the F1 domain, which matches the ground state structure of the isolated domain. Therefore, the present cryo-EM structure of FoF1 ATP synthase provides direct structural evidence for Boyer's binding change mechanism in the context of the intact enzyme.