Mass Spectrometry Centre, QOPNA, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal.
Rapid Commun Mass Spectrom. 2011 Jan 30;25(2):316-26. doi: 10.1002/rcm.4866.
The anionic phospholipid cardiolipin (CL) is found almost exclusively in the inner membrane of mitochondria, playing an important role in energy metabolism. Oxidation of CL has been associated with apoptotic events and various pathologies. In this study, electrospray ionization mass spectrometry coupled with liquid chromatography (LC/ESI-MS) was used to identify tetralinoleoyl-cardiolipin (TLCL) modifications induced by the OH(·) radical generated under Fenton reaction conditions (H(2)O(2) and Fe(2+)). The identified oxidation products of TLCL contained 2, 4, 6 and 8 additional oxygen atoms. These long-chain oxidation products were characterized by LC/ESI-MS/MS as doubly M-2H and singly charged M-H ions. A detailed analysis of the fragmentation pathways of these precursor ions allowed the identification of hydroperoxy derivatives of CL. MS/MS analysis indicated that CL oxidation products with 4, 6 and 8 oxygen atoms have one fatty acyl chain bearing 4 oxygen atoms (RCOO+4O). Even when the TLCL molecule was oxidized by the addition of eight oxygen atoms, one of the acyl chains remained non-modified and one fatty acyl chain contained three or four oxygen atoms. This led us to conclude that under oxidative conditions by the OH(·) radical, the distribution of oxygens/peroxy groups in the CL molecule is not random, even when CL has the same fatty acyl chains in all the positions. Using mass spectrometry, the oxidation products have been unequivocally assigned, which may be useful for their detection in biological samples.
阴离子磷脂心磷脂 (CL) 几乎只存在于线粒体的内膜中，在心磷脂在能量代谢中发挥着重要作用。CL 的氧化与细胞凋亡事件和各种病理有关。在这项研究中，电喷雾电离质谱 (ESI-MS) 与液相色谱 (LC/ESI-MS) 联用，用于鉴定由芬顿反应条件下 (H2O2 和 Fe2+) 生成的 OH·自由基引起的心磷脂 (TLCL) 的四油酰基修饰。鉴定出的 TLCL 氧化产物含有 2、4、6 和 8 个额外的氧原子。这些长链氧化产物通过 LC/ESI-MS/MS 鉴定为双 M-2H 和单电荷 M-H 离子。对这些前体离子的碎裂途径的详细分析允许鉴定 CL 的氢过氧化物衍生物。MS/MS 分析表明，具有 4、6 和 8 个氧原子的 CL 氧化产物具有一个带有 4 个氧原子的酰基链 (RCOO+4O)。即使 TLCL 分子通过添加八个氧原子被氧化，一个酰基链仍保持未修饰状态，一个脂肪酸链含有三个或四个氧原子。这使我们得出结论，在 OH·自由基的氧化条件下，CL 分子中的氧/过氧基的分布不是随机的，即使 CL 在所有位置都具有相同的脂肪酸链。使用质谱法，可以明确地分配氧化产物，这可能有助于它们在生物样品中的检测。
