Beckman J K, Borowitz S M, Burr I M
J Biol Chem. 1987 Feb 5;262(4):1479-84.
The involvement of phospholipase(s) A in lipid peroxidation of rat liver microsomes was investigated by: (a) determining the effects of phospholipase A inhibitors (p-bromophenylacyl bromide, chlorpromazine, mepacrine) on the accumulation of thiobarbituric acid reactivity or on levels of oxidized phospholipids in response to selected oxidative stimuli and (b) measurement of phospholipase A activities in response to these agents. Lipid peroxidation in response to various peroxidation systems was inhibited completely by exposure of microsomes to p-bromophenylacyl bromide (250 microM). The effectiveness of p-bromophenylacyl bromide was dependent on the presence of glutathione (200 microM) in preincubation mixtures. Chlorpromazine (100 microM) and mepacrine (100 microM) also effectively inhibited peroxidation, and their potency was independent of glutathione. The accumulation of oxidized phospholipids in response to the potent peroxidation stimulus alloxan/ferrous ion was similarly inhibited by p-bromophenylacyl bromide, although the level of oxidized phospholipid in response to the initiator ADP/ferrous ion was not affected. Microsomal phospholipase A1 activity, assessed using a liposomal substrate, was substantially enhanced by promoters of lipid peroxidation. Phospholipase A2 activity was not detected using a liposomal substrate but was evident using radiolabeled microsomes as endogenous substrate and was enhanced by oxidative stimuli. We conclude that phospholipase A activity may play an integral role in the microsomal lipid peroxidation mechanism. Based on this study, we hypothesize a role for phospholipases in facilitating propagation reactions.
通过以下方式研究了磷脂酶A在大鼠肝微粒体脂质过氧化中的作用：(a) 确定磷脂酶A抑制剂（对溴苯甲酰溴、氯丙嗪、米帕林）对硫代巴比妥酸反应性积累或对选定氧化刺激下氧化磷脂水平的影响，以及 (b) 测量对这些试剂的磷脂酶A活性。微粒体暴露于对溴苯甲酰溴（250 μM）可完全抑制对各种过氧化系统的脂质过氧化。对溴苯甲酰溴的有效性取决于预孵育混合物中谷胱甘肽（200 μM）的存在。氯丙嗪（100 μM）和米帕林（100 μM）也有效抑制过氧化，且其效力与谷胱甘肽无关。对溴苯甲酰溴同样抑制了对强力过氧化刺激物四氧嘧啶/亚铁离子的氧化磷脂积累，尽管对引发剂ADP/亚铁离子的氧化磷脂水平未受影响。使用脂质体底物评估的微粒体磷脂酶A1活性因脂质过氧化促进剂而显著增强。使用脂质体底物未检测到磷脂酶A2活性，但使用放射性标记的微粒体作为内源性底物时很明显，且因氧化刺激而增强。我们得出结论，磷脂酶A活性可能在微粒体脂质过氧化机制中起不可或缺的作用。基于这项研究，我们推测磷脂酶在促进传播反应中发挥作用。
