Johnson W Thomas, Johnson Lu Ann K, Lukaski Henry C
US Department of Agriculture, Agricultural Research Service, Grand Forks Human Nutrition Research Center, ND 58202-9034, USA.
J Nutr Biochem. 2005 Nov;16(11):682-92. doi: 10.1016/j.jnutbio.2005.03.009. Epub 2005 Aug 2.
Sensitivity of the assay for Cu,Zn superoxide dismutase 3 (SOD3), the predominant form of SOD in serum, can be increased, and interferences caused by low-molecular-weight substances in the serum can be reduced by conducting the assay at pH 10 with xanthine/xanthine oxidase and acetylated cytochrome c (cyt c) as superoxide generator and detector, respectively. Serum SOD3 activity was assayed under these conditions in an experiment where weanling, male rats were fed diets for 6 weeks containing 3, 5 and 15 mg Zn/kg with dietary Cu set at 0.3, 1.5 and 5 mg Cu/kg at each level of dietary Zn. Serum SOD3 responded to changes in dietary Cu but not to changes in dietary Zn. A second experiment compared serum SOD3 activity to traditional indices of Cu status in weanling, male and female rats after they were fed diets containing, nominally, 0, 1, 1.5, 2, 2.5, 3 and 6 mg Cu/kg for 6 weeks. Serum SOD3 activity was significantly lower (P < .05) in male rats fed diets containing 0 and 1 mg Cu/kg and female rats fed diet containing 0 mg Cu/kg compared with rats fed diet containing 6 mg Cu/kg. These changes were similar to changes in liver Cu concentrations, liver cyt c oxidase (CCO) activity and plasma ceruloplasmin in males and females. Serum SOD3 activity was also strongly, positively correlated with liver Cu concentrations over the entire range of dietary Cu concentrations (R(2) = .942 in males, R(2) = .884 in females, P < .0001). Plots of serum SOD3 activity, liver Cu concentration, liver CCO activity and ceruloplasmin as functions of kidney Cu concentration all had two linear segments that intersected at similar kidney Cu concentrations (18-22 microg/g dry kidney in males, 15-17 microg/g dry kidney in females). These findings indicate that serum SOD3 activity is a sensitive index of Cu status.
血清中主要形式的超氧化物歧化酶（SOD）即铜锌超氧化物歧化酶3（SOD3）检测的灵敏度可以提高，并且通过在pH 10条件下，分别以黄嘌呤/黄嘌呤氧化酶和乙酰化细胞色素c（细胞色素c）作为超氧化物生成剂和检测器进行检测，可以减少血清中低分子量物质引起的干扰。在一项实验中，对断奶雄性大鼠饲喂含锌量分别为3、5和15mg/kg的饲料，每种锌水平下的饲料铜含量设定为0.3、1.5和5mg/kg，持续6周，然后在上述条件下检测血清SOD3活性。血清SOD3对饲料铜含量的变化有反应，但对饲料锌含量变化无反应。第二项实验比较了断奶雄性和雌性大鼠在饲喂名义上含铜量为0、1、1.5、2、2.5、3和6mg/kg的饲料6周后血清SOD3活性与传统铜状态指标的情况。与饲喂含铜量为6mg/kg饲料的大鼠相比，饲喂含铜量为0和1mg/kg饲料的雄性大鼠以及饲喂含铜量为0mg/kg饲料的雌性大鼠血清SOD3活性显著降低（P < 0.05）。这些变化与雄性和雌性大鼠肝脏铜浓度、肝脏细胞色素c氧化酶（CCO）活性以及血浆铜蓝蛋白的变化相似。在整个饲料铜浓度范围内，血清SOD3活性与肝脏铜浓度也呈强正相关（雄性R(2) = 0.942，雌性R(2) = 0.884，P < 0.0001）。以血清SOD3活性、肝脏铜浓度、肝脏CCO活性和铜蓝蛋白作为肾脏铜浓度的函数作图，所有图均有两个线性段，它们在相似的肾脏铜浓度处相交（雄性为18 - 22μg/g干肾，雌性为15 - 17μg/g干肾）。这些发现表明血清SOD3活性是铜状态的一个敏感指标。
