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1.
软X射线不仅能引起红细胞表面电荷的变化,同时也能导致淋巴细胞和血小板表面电荷下降,表现为照射后它们的电泳率下降。低剂量范围内,这种电荷的变化是暂时性的,照后4小时降到最低点,24小时后恢复到对照的水平。细胞电泳率的下降与辐射剂量相关。淋巴细胞是一个复杂的细胞群,正常状态下,按细胞在电场中泳动速度的快慢,可分为两个组分:快峰为T细胞,慢峰为B细胞。软X射线照射以后,T和B细胞的电泳率皆减慢,频数分布峰值下降,离散度加大。血小板成分单一,电泳率较一致。 从照射浓集的血小板再加回自身血浆中电泳率的下降较照射血浆再加到血小板中的电泳率下降大得多;受照射的血小板在磷酸缓冲液中电泳率下降较在血浆悬液中严重得多;2000 rad照后,悬浮于血浆中的血小板电泳率能恢复,而悬浮于磷酸缓冲液中则不能恢复,三个方面来看,血浆中可能存在抗辐射因子。超氧化物岐化酶能有效地预防血小板电泳率的下降,从而可阻止血小板的凝聚。 相似文献
2.
Total superoxide dismutase (SOD:superoxide: superoxide oxidoreductase; EC 1.15.1.1) activity and individual activities of its three different metalloenzymes, CuZn-SOD, Fe-SOD, and Mn-SOD, were investigated during senescence of apples (Malus domestica Borkh.). Total SOD activity and relative activities of its three forms varied greatly among cultivars. Activities underwent considerable change during senescence of fruit, but changes were different among cultivars. Whether fruit senesced at 0°C or 20°C had little effect on SOD activities, and application of the antioxidant diphenylamine (DPA) did not alter activities. SOD activities increased with occurrence of the physiological disorder “senescent breakdown,” but did not increase with occurrence of the disorder “superficial scald.” In a given apple cultivar, changes in total SOD activity generally paralleled activities of the different SOD forms. Such activity may reflect changes affecting food and nutritive quality of the fruit. 相似文献
3.
仙人掌超氧化物歧化酶的纯化及其部分性质研究 总被引:9,自引:0,他引:9
10 0 0g仙人掌茎经匀浆、硫酸铵分级沉淀、SephadexG - 75凝胶层析和DEAE - 5 2离子交换层析 3个步骤 ,将仙人掌SOD纯化到SDS -PAGE均一纯 ,得白色粉状SOD 0 8985g ,比活 910U/mg,活力回收 4 3 1% ,纯化倍数 76。该酶相对分子质量 37 1kD ,H2 O2 和KCN的抑制实验结果表明为Cu、Zn -SOD。该酶的最大紫外吸收在 2 75nm处。 5 0℃保温 15 0min ,SOD的活性不变 ,在pH =5 0~ 9 0时SOD有较好的稳定性 相似文献
4.
对生物体内和模拟的含锰金属酶,即含锰超氧化物歧化酶(Mn—SOD)、含锰的过氧化氢酶(Mn—catalase)及含锰的光合成氧释放配合物(Mn—OEC)的结构、活性部位、催化作用机理及其模型化合物的研究进展进行了综述。 相似文献
5.
6.
Ssu-Han Chen Shih-Jiuan Chiu Teh-Min Hu 《International journal of molecular sciences》2012,13(11):13985-14001
Nitric oxide (NO) is an important molecule that exerts multiple functions in biological systems. Because of the short-lived nature of NO, S-nitrosothiols (RSNOs) are believed to act as stable NO carriers. Recently, sulfhydryl (SH) containing macromolecules have been shown to be promising NO carriers. In the present study, we aimed to synthesize and characterize a potential NO carrier based on bovine Cu,Zn-superoxide dismutase (bSOD). To prepare S-nitrosated bSOD, the protein was incubated with S-nitrosoglutathione (GSNO) under varied experimental conditions. The results show that significant S-nitrosation of bSOD occurred only at high temperature (50 °C) for prolonged incubation time (>2 h). S-nitrosation efficiency increased with reaction time and reached a plateau at ~4 h. The maximum amount of NO loaded was determined to be about 0.6 mol SNO/mol protein (~30% loading efficiency). The enzymatic activity of bSOD, however, decreased with reaction time. Our data further indicate that NO functionality can only be measured in the presence of extremely high concentrations of Hg2+ or when the protein was denatured by guanidine. Moreover, mildly acidic pH was shown to favor S-nitrosation of bSOD. A model based on unfolding and refolding of bSOD during preparation was proposed to possibly explain our observation. 相似文献
7.
Jeffrey J. Liu Daniel E. Diaz David A. Quist Kenneth D. Karlin 《Israel journal of chemistry》2016,56(9-10):738-755
Primary copper(I)-dioxygen (O2) adducts, cupric-superoxide complexes, have been proposed intermediates in copper-containing dioxygen-activating monooxygenase and oxidase enzymes. Here, mechanisms of C−H activation by reactive copper-(di)oxygen intermediates are discussed, with an emphasis on cupric-superoxide species. Over the past 25 years, many synthetically derived cupric-superoxide model complexes have been reported. Due to the thermal instability of these intermediates, early studies focused on increasing their stability and obtaining physical characterization. More recently, in an effort to gain insight into the possible substrate oxidation step in some copper monooxygenases, several cupric-superoxide complexes have been used as surrogates to probe substrate scope and reaction mechanisms. These cupric superoxides are capable of oxidizing substrates containing weak O−H and C−H bonds. Mechanistic studies for some enzymes and model systems have supported an initial hydrogen-atom abstraction via the cupric-superoxide complex as the first step of substrate oxidation. 相似文献
8.
Inside Cover: Pro‐oxidant and Antioxidant Effects in Photodynamic Therapy: Cells Recognise that Not All Exogenous ROS Are Alike (ChemBioChem 9/2016) 下载免费PDF全文
9.
通过研究Nd3+、Er3+、Gd3+和La3+稀土离子对枯草芽孢杆菌在生长过程中所产的超氧化物歧化酶活性的影响,来探讨稀土可能会导致生物体发生氧化损伤。利用改良的邻苯三酚自氧化法测定超氧化物歧化酶活性。结果表明:4种稀土离子对其细胞中超氧化物歧化酶活性均有抑制作用,且Nd3+的抑制作用较其它3种稀土离子要强,故一定浓度的稀土离子很有可能会导致生物体发生氧化损伤。4种稀土离子的浓度不同影响有所不同,总的来说,稀土离子的浓度越大,对枯草杆菌抗氧化的抑制作用越明显,损伤毒性作用越强。 相似文献
10.
In monocarpic plants, stem cells are fated to die. However, the potential mechanism of stem cell death has remained elusive. Here, we reveal that the levels of two forms of reactive oxygen species (ROS), superoxide anion free radical () and hydrogen peroxide (H2O2), show dynamic changes in the shoot apex during the plant life cycle of Arabidopsis thaliana. We found that the level of decreased and disappeared at four weeks after bolting (WAB), while H2O2 appeared at 3 WAB and showed a burst at 5 WAB. The timing of dynamic changes in and H2O2 was delayed for approximately three weeks in clv3-2, which has a longer lifespan. Moreover, exogenous application of H2O2 inhibited the expression of the stem cell determinant WUSCHEL (WUS) and promoted the expression of the developmentally programmed cell death (dPCD) marker gene ORESARA 1 (ORE1). These results indicate that H2O2 triggers an important signal inducing dPCD in stem cells. Given that plays roles in maintaining WUS expression and stem cell activity, we speculate that the dynamic shift from to H2O2 in the shoot apex results in stem cell death. Our findings provide novel insights for understanding ROS-mediated regulation during plant stem cell death. 相似文献