Galkin Alexander, Dröse Stefan, Brandt Ulrich
Universität Frankfurt, Fachbereich Medizin, Zentrum der Biologischen Chemie, Molekulare Bioenergetik, Theodor-Stern-Kai 7, Haus 26, D-60590 Frankfurt am Main, Germany.
Biochim Biophys Acta. 2006 Dec;1757(12):1575-81. doi: 10.1016/j.bbabio.2006.10.001. Epub 2006 Oct 7.
ubiquinone oxidoreductase (complex I) is the largest and most complicated enzyme of aerobic electron transfer. The mechanism how it uses redox energy to pump protons across the bioenergetic membrane is still not understood. Here we determined the pumping stoichiometry of mitochondrial complex I from the strictly aerobic yeast Yarrowia lipolytica. With intact mitochondria, the measured value of 3.8H(+)/2e indicated that four protons are pumped per NADH oxidized. For purified complex I reconstituted into proteoliposomes we measured a very similar pumping stoichiometry of 3.6H(+)/2e . This is the first demonstration that the proton pump of complex I stayed fully functional after purification of the enzyme.
泛醌氧化还原酶（复合体I）是需氧电子传递中最大且最复杂的酶。其利用氧化还原能量将质子泵过生物能膜的机制仍不为人所知。在此，我们测定了严格需氧酵母解脂耶氏酵母线粒体复合体I的质子泵化学计量。对于完整的线粒体，测得的值为3.8H⁺/2e，表明每氧化一分子NADH会泵出四个质子。对于重构到蛋白脂质体中的纯化复合体I，我们测得非常相似的质子泵化学计量为3.6H⁺/2e。这是首次证明复合体I的质子泵在酶纯化后仍保持完全功能。
