Benzophenone-sensitized photooxidation of sarcoplasmic reticulum membranes: site-specific modification of the Ca(2+)-ATPase.
Benzophenone-sensitized photooxidation of sarcoplasmic reticulum membranes: site-specific modification of the Ca(2+)-ATPase.
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DOI：
10.1016/s0891-5849(97)00131-7
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发表时间：
1997
影响因子：
7.4
通讯作者：
A. Krainev;R. Viner;D. Bigelow
中科院分区：
文献类型：
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作者：
A. Krainev;R. Viner;D. Bigelow
通过硬脂酸自旋标记动力学评估，二苯甲酮（BP）被用作光敏剂，在BP浓度不扰乱双层结构的情况下，在模型和天然生物膜中引发脂质过氧化。照射到肌浆网膜（SR）中的BP会导致BP呈指数衰减，共轭二烯和其他脂质过氧化产物呈线性积累，正如之前在亚油酸胶束中观察到的那样[Marcovic和Patterson]。Photochem。光化学学报，2003,18(4):393 - 398。与不含蛋白质的脂质囊泡相比，SR中膜跨越蛋白的存在显著抑制了脂质过氧化，这表明引发剂（三态BP）和BP衍生的自由基与蛋白质基团发生了竞争性反应。主要的整体膜蛋白Ca2+- atp酶的修饰通过Ca2+- atp酶氨基酸组成的变化及其功能抑制来证明。钙转运速率呈指数衰减直至完成，而钙依赖性atp酶活性在适度失活之前表现出初始滞后。这些结果与钙转运位点在跨膜肽内的定位和atp结合位点在Ca2+- atp酶的胞质结构域内的定位一致，进一步表明BP的光敏化模拟了SR膜疏水内部的氧化应激。
Benzophenone (BP) was used as a photosensitizer to initiate lipid peroxidation in model and native biological membranes at concentrations of BP that do not perturb bilayer structure, as assessed by stearic acid spin label dynamics. Illumination of BP partitioned into sarcoplasmic reticulum membranes (SR) results in an exponential decay of BP and a linear accumulation of conjugated dienes and other products of lipid peroxidation as observed previously for micelles of linoleic acid [Marcovic and Patterson. Photochem. Photobiol. 58:329–334, 1993]. Lipid peroxidation was substantially inhibited in the presence of membrane-spanning proteins in SR compared to protein-free lipid vesicles, suggesting the competitive reaction of the initiator (triplet BP) and BP-derived radical species with protein groups. Modification of the predominant integral membrane protein, the Ca2+-ATPase, was demonstrated by changes in Ca2+-ATPase amino acid composition as well as by its functional inhibition. The rate of calcium transport showed an immediate exponential decay to completion, while calcium-dependent ATPase activity exhibited an initial lag before modest inactivation. These results are consistent with the respective localization of calcium transport sites within membrane-spanning peptides and the ATP-binding site within the cytosolic domain of the Ca2+-ATPase, further suggesting that photosensitization of BP models oxidative stress inside the hydrophobic interior of the SR membrane.