Piccirella Simona, Czegle Ibolya, Lizák Beáta, Margittai Eva, Senesi Silvia, Papp Eszter, Csala Miklós, Fulceri Rosella, Csermely Péter, Mandl József, Benedetti Angelo, Bánhegyi Gábor
Department of Medical Chemistry, Molecular Biology, and Pathobiochemistry, Semmelweis University, Budapest, Hungary.
J Biol Chem. 2006 Feb 24;281(8):4671-7. doi: 10.1074/jbc.M509406200. Epub 2005 Dec 22.
The redox state of the intraluminal pyridine nucleotide pool was investigated in rat liver microsomal vesicles. The vesicles showed cortisone reductase activity in the absence of added reductants, which was dependent on the integrity of the membrane. The intraluminal pyridine nucleotide pool could be oxidized by the addition of cortisone or metyrapone but not of glutathione. On the other hand, intraluminal pyridine nucleotides were slightly reduced by cortisol or glucose 6-phosphate, although glutathione was completely ineffective. Redox state of microsomal protein thiols/disulfides was not altered either by manipulations affecting the redox state of pyridine nucleotides or by the addition of NAD(P)+ or NAD(P)H. The uncoupling of the thiol/disulfide and NAD(P)+/NAD(P)H redox couples was not because of their subcompartmentation, because enzymes responsible for the intraluminal oxidoreduction of pyridine nucleotides were distributed equally in smooth and rough microsomal subfractions. Instead, the phenomenon can be explained by the negligible representation of glutathione reductase in the endoplasmic reticulum lumen. The results demonstrated the separate existence of two redox systems in the endoplasmic reticulum lumen, which explains the contemporary functioning of oxidative folding and of powerful reductive reactions.
在大鼠肝脏微粒体囊泡中研究了腔内吡啶核苷酸池的氧化还原状态。在不添加还原剂的情况下，这些囊泡表现出可的松还原酶活性，该活性依赖于膜的完整性。通过添加可的松或甲吡酮可氧化腔内吡啶核苷酸池，但添加谷胱甘肽则不能。另一方面，尽管谷胱甘肽完全无效，但皮质醇或6-磷酸葡萄糖可使腔内吡啶核苷酸略有还原。影响吡啶核苷酸氧化还原状态的操作或添加NAD(P)+或NAD(P)H均未改变微粒体蛋白硫醇/二硫键的氧化还原状态。硫醇/二硫键和NAD(P)+/NAD(P)H氧化还原对的解偶联并非由于它们的亚区室化，因为负责腔内吡啶核苷酸氧化还原的酶在光滑和粗糙微粒体亚组分中分布均匀。相反，这种现象可以用内质网腔中谷胱甘肽还原酶的含量可忽略不计来解释。结果表明内质网腔中存在两个独立的氧化还原系统，这解释了氧化折叠和强大还原反应同时发挥作用的现象。
