Zhu Jian-Hong, Zhang Xiaomei, Roneker Carol A, McClung James P, Zhang Sheng, Thannhauser Theodore W, Ripoll Daniel R, Sun Qi, Lei Xin Gen
Department of Animal Science, Cornell University, Ithaca, NY 14853, USA.
Free Radic Biol Med. 2008 Sep 1;45(5):611-8. doi: 10.1016/j.freeradbiomed.2008.05.018. Epub 2008 May 28.
The only known function of Cu,Zn-superoxide dismutase (SOD1) is to catalyze the dismutation of superoxide anion into hydrogen peroxide. Our objective was to determine if SOD1 catalyzes murine liver protein nitration induced by acetaminophen (APAP) and lipopolysaccharide (LPS). Liver and plasma samples were collected from young adult SOD1 knockout mice (SOD1-/-) and wild-type (WT) mice at 5 or 6 h after an ip injection of saline, APAP, or LPS. Hepatic nitrotyrosine formation was induced by APAP and LPS only in the WT mice. The diminished hepatic protein nitration in the SOD1-/- mice was not directly related to plasma nitrite and nitrate concentrations. Similar genotype differences were seen in liver homogenates treated with a bolus of peroxynitrite. Adding only the holo-, and not the apo-, SOD1 enzyme into the liver homogenates enhanced the reaction in an activity-dependent fashion and nearly eliminated the genotype difference at the high doses. Mass spectrometry showed four more nitrotyrosine residues in bovine serum albumin and 10 more nitrated protein candidates in the SOD1-/- liver homogenates by peroxynitrite with added SOD1. In conclusion, the diminished hepatic protein nitration mediated by APAP or LPS in the SOD1-/- mice is due to the lack of SOD1 activity per se.
铜锌超氧化物歧化酶（SOD1）唯一已知的功能是催化超氧阴离子歧化为过氧化氢。我们的目的是确定SOD1是否催化对乙酰氨基酚（APAP）和脂多糖（LPS）诱导的小鼠肝脏蛋白硝化。在腹腔注射生理盐水、APAP或LPS后5或6小时，从年轻成年SOD1基因敲除小鼠（SOD1-/-）和野生型（WT）小鼠中采集肝脏和血浆样本。仅在WT小鼠中，APAP和LPS诱导了肝脏硝基酪氨酸的形成。SOD1-/-小鼠肝脏蛋白硝化减少与血浆亚硝酸盐和硝酸盐浓度无直接关系。在用过氧亚硝酸盐处理的肝脏匀浆中也观察到类似的基因型差异。仅向肝脏匀浆中添加全酶形式而非脱辅基形式的SOD1酶，以活性依赖的方式增强了反应，并在高剂量时几乎消除了基因型差异。质谱分析显示，添加SOD1的过氧亚硝酸盐使牛血清白蛋白中多了4个硝基酪氨酸残基，SOD1-/-肝脏匀浆中有10种更多的硝化蛋白候选物。总之，SOD1-/-小鼠中由APAP或LPS介导的肝脏蛋白硝化减少是由于缺乏SOD1活性本身。
