کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5507155 | 1400314 | 2017 | 47 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Time-resolved generation of membrane potential by ba3 cytochrome c oxidase from Thermus thermophilus coupled to single electron injection into the O and OH states
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کلمات کلیدی
PLSBNCTRISThermus thermophilusProton loading siteΔψ - Δρtransmembrane electric potential difference - اختلاف پتانسیل الکتریکی فرابنفشTris(hydroxymethyl)aminomethane - تریس (هیدروکسی متیل) آمینومتانTime constant - ثابت زمانیRubpy - خربزهcytochrome c oxidase - سیتوکروم سی اکسیدازMembrane potential - پتانسیل غشاء
موضوعات مرتبط
علوم زیستی و بیوفناوری
علوم کشاورزی و بیولوژیک
دانش گیاه شناسی
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
Two electrogenic phases with characteristic times of ~ 14 μs and ~ 290 μs are resolved in the kinetics of membrane potential generation coupled to single-electron reduction of the oxidized “relaxed” O state of ba3 oxidase from T. thermophilus (O â E transition). The rapid phase reflects electron redistribution between CuA and heme b. The slow phase includes electron redistribution from both CuA and heme b to heme a3, and electrogenic proton transfer coupled to reduction of heme a3. The distance of proton translocation corresponds to uptake of a proton from the inner water phase into the binuclear center where heme a3 is reduced, but there is no proton pumping and no reduction of CuB. Single-electron reduction of the oxidized “unrelaxed” state (OH â EH transition) is accompanied by electrogenic reduction of the heme b/heme a3 pair by CuA in a “fast” phase (~ 22 μs) and transfer of protons in “middle” and “slow” electrogenic phases (~ 0.185 ms and ~ 0.78 ms) coupled to electron redistribution from the heme b/heme a3 pair to the CuB site. The “middle” and “slow” electrogenic phases seem to be associated with transfer of protons to the proton-loading site (PLS) of the proton pump, but when all injected electrons reach CuB the electronic charge appears to be compensated by back-leakage of the protons from the PLS into the binuclear site. Thus proton pumping occurs only to the extent of ~ 0.1 H+/eâ, probably due to the formed membrane potential in the experiment.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Biochimica et Biophysica Acta (BBA) - Bioenergetics - Volume 1858, Issue 11, November 2017, Pages 915-926
Journal: Biochimica et Biophysica Acta (BBA) - Bioenergetics - Volume 1858, Issue 11, November 2017, Pages 915-926
نویسندگان
Sergey A. Siletsky, Ilya Belevich, Nikolai P. Belevich, Tewfik Soulimane, MÃ¥rten Wikström,