The membrane portion of F(0)F(1)-ATP synthase, F(0), translocates protons by a rotary mechanism. Proton conduction by F(0) was studied in chromatophores of the photosynthetic bacterium Rhodobacter capsulatus. The discharge of a light-induced voltage jump was monitored by electrochromic absorption transients to yield the unitary conductance of F(0). The current-voltage relationship of F(0) was linear from 7 to 70 mV. The current was extremely proton-specific (>10(7)) and varied only slightly ( approximately threefold) from pH 6 to 10. The maximum conductance was approximately 10 fS at pH 8, equivalent to 6240 H(+) s(-1) at 100-mV driving force, which is an order-of-magnitude greater than of coupled F(0)F(1). There was no voltage-gating of F(0) even at low voltage, and proton translocation could be driven by deltapH alone, without voltage. The reported voltage gating in F(0)F(1) is thus attributable to the interaction of F(0) with F(1) but not to F(0) proper. We simulated proton conduction by a minimal rotary model including the rotating c-ring and two relay groups mediating proton exchange between the ring and the respective membrane surface. The data fit attributed pK values of approximately 6 and approximately 10 to these relays, and placed them close to the membrane/electrolyte interface.
CHS is an independent publication series and publishes a wide variety of material in the field of circumpolar health and wellbeing. It is intended that the produced material is of considerable value for health care professionals and officials in circumpolar areas, or may otherwise be useful for health care development and practices in the circumpolar areas. It is planned, and depending on our clients and collaborators needs, that we will publish a varying amount of supplements annually. At this moment the first issue of the Circumpolar Health Supplements is available at the web pages of Int J Circumpolar Health (IJCH) (www.ijch.fi). This issue has also been distributed to all subscribers of IJCH free of charge. At present we are preparing to include the new supplement series in the different indexes. How to subscribe, how to conduct group orders of hard copies, and other practical issues will be detailed at the web pages of IJCH. This information will be also be indicated in the coming issues of IJCH and the next issue of CHS, which will be published in
Vital capacitySmoking and respiratory diseases the interrelations of community members, the social arrangement of traditional Arctic communities also creates an optimal balance with the environment. Therefore, the human infringements on the Arctic's natural environment in the "new industrial development areas" result not only in eco-catastrophes but also in social reorganization. Today, the nomadic and semi-nomadic groups still maintain a way of life that is close to tradition and is based on reindeer herding,
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