Brame Cynthia J, Boutaud Olivier, Davies Sean S, Yang Tao, Oates John A, Roden Dan, Roberts L Jackson
Departments of Pharmacology and Medicine, Vanderbilt University, Nashville, Tennessee 27232-6602, USA.
J Biol Chem. 2004 Apr 2;279(14):13447-51. doi: 10.1074/jbc.M313349200. Epub 2004 Jan 10.
Oxidative stress frequently leads to altered function of membrane proteins. Isoketals are highly reactive products of the isoprostane pathway of free radical-induced lipid peroxidation that rapidly form covalent protein adducts and exhibit a remarkable proclivity to form protein cross links in vitro. Examination of isoketal adducts from an animal model of oxidative injury revealed that initial adducts were formed by isoketals esterified in phospholipids, representing a novel oxidative injury-associated modification of proteins by phospholipids. Maturation of adducts involved cleavage from phospholipids and conversion of adducts to a more stable chemical form that can be detected for extended periods. Because initial adducts were formed by phospholipid-esterified isoketals, the functional consequence of isoketal adduction was examined using a model membrane protein (a cardiac K(+) channel). These studies revealed that isoketal adduction profoundly altered protein function, inhibiting potassium current in a dose-dependent manner. These findings indicate that phospholipid-esterified isoketals rapidly adduct membrane proteins and that such modification can alter protein function, suggesting a generalized cellular mechanism for alteration of membrane function as a consequence of oxidative stress.
氧化应激常常导致膜蛋白功能改变。异前列腺素是自由基诱导的脂质过氧化的异前列腺素途径的高反应性产物，能迅速形成共价蛋白加合物，且在体外表现出显著的形成蛋白交联的倾向。对氧化损伤动物模型中的异前列腺素加合物进行检测发现，最初的加合物是由磷脂中酯化的异前列腺素形成的，这代表了一种由磷脂介导的与氧化损伤相关的新型蛋白修饰。加合物的成熟过程包括从磷脂上裂解下来，并转化为一种更稳定的化学形式，以便能在较长时间内被检测到。由于最初的加合物是由磷脂酯化的异前列腺素形成的，因此使用一种模型膜蛋白（一种心脏钾通道）来研究异前列腺素加合的功能后果。这些研究表明，异前列腺素加合会深刻改变蛋白功能，以剂量依赖的方式抑制钾电流。这些发现表明，磷脂酯化的异前列腺素能迅速与膜蛋白加合，且这种修饰可改变蛋白功能，提示这是氧化应激导致膜功能改变的一种普遍细胞机制。
