The Mg2+-containing Water Cluster of Mammalian Cytochrome c Oxidase Collects Four Pumping Proton Equivalents in Each Catalytic Cycle.

Bovine heart cytochrome c oxidase (CcO) pumps four proton equivalents per catalytic cycle through the H-pathway, a proton-conducting pathway, which includes a hydrogen bond network and a water channel operating in tandem. Protons are transferred by HO through the water channel from the N-side into the hydrogen bond network, where they are pumped to the P-side by electrostatic repulsion between protons and net positive charges created at heme a as a result of electron donation to O bound to heme a To block backward proton movement, the water channel remains closed after O binding until the sequential four-proton pumping process is complete. Thus, the hydrogen bond network must collect four proton equivalents before O binding.

Determination of damage-free crystal structure of an X-ray-sensitive protein using an XFEL.

We report a method of femtosecond crystallography for solving radiation damage-free crystal structures of large proteins at sub-angstrom spatial resolution, using a large single crystal and the femtosecond pulses of an X-ray free-electron laser (XFEL). We demonstrated the performance of the method by determining a 1.9-Å radiation damage-free structure of bovine cytochrome c oxidase, a large (420-kDa), highly radiation-sensitive membrane protein.

Analysis of cardiopulmonary stress during endoscopy: is unsedated transnasal esophagogastroduodenoscopy appropriate for elderly patients?

Background: Transnasal esophagogastroduodenoscopy (EGD) without sedation has been reported to be safe and tolerable. It has recently been used widely in Japan for the detection of upper gastrointestinal disease. Alternatively, transoral examination using a thin endoscope has also been reported to be highly tolerable.

Dietary saury oil reduces hyperglycemia and hyperlipidemia in diabetic KKAy mice and in diet-induced obese C57BL/6J mice by altering gene expression.

We investigated the effect of saury oil on the alleviation of metabolic syndrome in mice. Saury oil contains 18% (w/w/) n-3 polyunsaturated fatty acids (n-3 PUFA) and 35% (w/w) monounsaturated fatty acids (MUFA). Diabetic KKAy mice were fed a 10% soybean oil diet (control) or a 10% saury oil diet for 4 weeks, and diet-induced obese C57BL/6J mice were fed a high-fat diet containing 32% lard (control) or 22% lard plus 10% saury oil for 6 weeks.