Ursini F, Maiorino M, Gregolin C
Biochim Biophys Acta. 1985 Mar 29;839(1):62-70. doi: 10.1016/0304-4165(85)90182-5.
The reduction of membrane-bound hydroperoxides is a major factor acting against lipid peroxidation in living systems. This paper presents the characterization of the previously described 'peroxidation-inhibiting protein' as a 'phospholipid hydroperoxide glutathione peroxidase'. The enzyme is a monomer of 23 kDa (SDS-polyacrylamide gel electrophoresis). It contains one gatom Se/22 000 g protein. Se is in the selenol form, as indicated by the inactivation experiments in the presence of iodoacetate under reducing conditions. The glutathione peroxidase activity is essentially the same on different phospholipids enzymatically hydroperoxidized by the use of soybean lipoxidase (EC 1.13.11.12) in the presence of deoxycholate. The kinetic data are compatible with a tert-uni ping-pong mechanism, as in the case of the 'classical' glutathione peroxidase (EC 1.11.1.9). The second-order rate constants (K1) for the reaction of the enzyme with the hydroperoxide substrates indicate that, while H2O2 is reduced faster by the glutathione peroxidase, linoleic acid hydroperoxide is reduced faster by the present enzyme. Moreover, the phospholipid hydroperoxides are reduced only by the latter. The dramatic stimulation exerted by Triton X-100 on the reduction of the phospholipid hydroperoxides suggests that this enzyme has an 'interfacial' character. The similarity of amino acid composition, Se content and kinetic mechanism, relative to the difference in substrate specificity, indicates that the two enzymes 'classical' glutathione peroxidase and phospholipid hydroperoxide glutathione peroxidase are in some way related. The latter is apparently specialized for lipophylic, interfacial substrates.
膜结合氢过氧化物的还原是生物系统中对抗脂质过氧化的一个主要因素。本文描述了先前所述的“过氧化抑制蛋白”为“磷脂氢过氧化物谷胱甘肽过氧化物酶”。该酶是一种23 kDa的单体（SDS-聚丙烯酰胺凝胶电泳）。它含有1个硒原子/22000克蛋白质。在还原条件下，碘乙酸存在时的失活实验表明，硒以硒醇形式存在。在脱氧胆酸盐存在下，使用大豆脂氧化酶（EC 1.13.11.12）对不同的磷脂进行酶促氢过氧化时，谷胱甘肽过氧化物酶活性基本相同。动力学数据与乒乓机制相符，就像“经典”谷胱甘肽过氧化物酶（EC 1.11.1.9）的情况一样。该酶与氢过氧化物底物反应的二级速率常数（K1）表明，虽然谷胱甘肽过氧化物酶还原H2O2更快，但本酶还原亚油酸氢过氧化物更快。此外，只有后者能还原磷脂氢过氧化物。Triton X-100对磷脂氢过氧化物还原的显著刺激表明该酶具有“界面”特性。氨基酸组成、硒含量和动力学机制的相似性，相对于底物特异性的差异，表明“经典”谷胱甘肽过氧化物酶和磷脂氢过氧化物谷胱甘肽过氧化物酶这两种酶在某种程度上是相关的。后者显然专门作用于亲脂性的界面底物。
