Kay Christopher W M, Mennenga Bina, Görisch Helmut, Bittl Robert
Institut für Experimentalphysik, Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany.
FEBS Lett. 2004 Apr 23;564(1-2):69-72. doi: 10.1016/S0014-5793(04)00317-5.
The binding pocket of the pyrroloquinoline quinone (PQQ) cofactor in quinoprotein alcohol dehydrogenases contains a characteristic disulphide ring formed by two adjacent cysteine residues. To analyse the function of this unusual structural motif we have investigated the wild-type and a double cysteine:alanine mutant of the quinoprotein ethanol dehydrogenase from Pseudomonas aeruginosa by electron paramagnetic resonance (EPR) spectroscopy. Thus, we have obtained the principal values for the full rhombic g-tensor of the PQQ semiquinone radical by high-field (94 GHz) EPR necessary for a discrimination of radical species in dehydrogenases containing PQQ together with other redox-active cofactors. Our results show that the characteristic disulphide ring is no prerequisite for the formation of the functionally important semiquinone form of PQQ.
醌蛋白醇脱氢酶中吡咯喹啉醌（PQQ）辅因子的结合口袋包含一个由两个相邻半胱氨酸残基形成的特征性二硫环。为了分析这种不同寻常的结构基序的功能，我们通过电子顺磁共振（EPR）光谱研究了铜绿假单胞菌醌蛋白乙醇脱氢酶的野生型和双半胱氨酸：丙氨酸突变体。因此，我们通过高场（94 GHz）EPR获得了PQQ半醌自由基完整菱形g张量的主值，这对于区分含有PQQ以及其他氧化还原活性辅因子的脱氢酶中的自由基种类是必要的。我们的结果表明，特征性二硫环不是形成功能上重要的PQQ半醌形式的先决条件。
