Superoxide anion is involved in the breakdown of endothelium-derived vascular relaxing factor

Endothelium-derived vascular relaxing factor (EDRF) is a humoral agent that is released by vascular endothelium and mediates vasodilator responses induced by various substances including acetylcholine and bradykinin. EDRF is very unstable, with a half-life of between 6 and 50 s, and is clearly distinguishable from prostacyclin. The chemical structure of EDRF is unknown but it has been suggested that it is either a hydroperoxy- or free radical-derivative of arachidonic acid or an unstable aldehyde, ketone or lactone. We have examined the role of superoxide anion (O-2) in the inactivation of EDRF released from vascular endothelial cells cultured on microcarrier beads and bioassayed using a cascade of superfused aortic smooth muscle strips. With this system, we have now demonstrated that EDRF is protected from breakdown by superoxide dismutase (SOD) and Cu2+, but not by catalase, and is inactivated by Fe2+. These findings indicate that O-2 contributes significantly to the instability of EDRF.     

Oxygen intermediates are triggered early in the cytolytic pathway of human NK cells

The mechanism of tumour cell destruction by natural killer (NK) cells or other lymphocytes is not understood. NK cells appear to represent a primitive anti-tumour surveillance system more analogous to macrophages than lymphocytes. Free oxygen radicals (O-2, OH) and H2O2 are thought to be involved in cell destruction by macrophages and therefore we looked for similar cytocidal intermediates of oxygen in NK cells. These highly reactive molecular species can easily be detected in the presence of luminol by the emission of light. We show here that highly enriched human NK cells respond to NK-sensitive but not NK-insensitive tumour cells with a rapid burst of oxygen metabolites as detected both by chemiluminescence and cytochrome c reduction. Agents which can prevent chemiluminescence and cytochrome c reduction, such as superoxide dismutase (SOD), reduced NK-mediated cytolysis and agents which increased chemiluminescence, such as interferon, also increased NK-mediated cytolysis. These results suggest that the production of oxygen species may be the earliest event to occur in the NK cell following tumour cell contact, and these products are involved in NK-mediated cytolysis.     

超氧化物歧化酶(SOD)的应用研究进展

超氧化物歧化酶(SOD)广泛存在与一切生物机体内,通过催化超氧阴离子自由基(O2-)发生歧化反应,减轻或消除超氧阴离子自由基(O2-)对机体的损害。本文介绍了超氧化物歧化酶(SOD)的基本类型和SOD在医药、食品、农业、化妆品等上的应用。     

The first observation of Mo5+ in the passivation layer of Mo2N

Molybdenum nitride powder with sg of 115 m2·g-1 (passivated) has been prepared by a temperature programmed reaction of MoO3 in H2/N2 mixture. It exhibited high catalytic activity in CO oxidation at low temperature. XPS, EPR and LRS studies have shown the existence of mixed valence states of Mo ions, especially Mo5+ ion (g⊥=1.932, g‖=1.892) observed for the first time, in the passivation layer of molybdenum nitride. A surface superoxide species, O-2(g = 2.001, Raman band 1 124 cm-1), was found to be produced accompanying the transformation of Mo5+/Mo4+ redox pair. Evidence has been given to suggest that this surface superoxide might be responsible for CO oxidation over Mo2N catalyst.     

天然与修饰超氧化物歧化酶某些物化性质的比较

本文对天然与月桂酸修饰的超氧化物歧化酶的某些物化性质进行了比较，结果表明，修饰酶较天然酶的稳定性显著增加，且保留了天然酶的大部分活性，具有广泛的应用前景。     

湖北盘腹蚁属一新种记述（膜翅目：蚁科）

湖北盘腹蚁属一新种记述（膜翅目：蚁科）王维郑哲民（陕西师范大学动物研究所，西安７１００６２；第一作者，男，３１岁，讲师）笔者在整理采自湖北省利川市的蚂蚁标本时，发现一新种，现记述如下．模式标本保存在陕西师范大学动物研究所标本室．凹唇盘腹蚁Ａｐｈａｅｎ...     

超氧阴离子自由基(O_2~-)导致红细胞膜蛋白交联作用的机理探讨

用邻苯三酚在碱性条件下自氧化产生的超氧阴离子自由基(O_2~-处理人红细胞膜导致膜蛋白交联形成高分子聚合物(HMP).用一定量的超氧化物歧化酶(SOD)预处理红细胞膜,HMP明显减少.用巯基抑制剂N-乙基马来酰胺(NEM)预处理红细胞膜,则HMP几乎消失.用特异性标记巯基的荧光探针N-(3-芘)马来酰胺(N-[3-P]NEM)来研究经不同浓度邻苯三酚处理的红细胞膜的荧光强度.结果表明,随着邻苯三酚浓度增高,荧光强度相应降低.上述结果提示,O_2~-可能主要是通过氧化巯基导致膜蛋白交联并形成HMP.     

Faster superoxide dismutase mutants designed by enhancing electrostatic guidance.

The enzyme Cu, Zn superoxide dismutase (SOD) protects against oxidative damage by dismuting the superoxide radical O2-. to molecular oxygen and hydrogen peroxide at the active-site Cu ion in a reaction that is rate-limited by diffusion and enhanced by electrostatic guidance. SOD has evolved to be one of the fastest enzymes known (V(max) approximately 2 x 10(9) M-1 s-1). The new crystal structures of human SOD show that amino-acid site chains that are implicated in electrostatic guidance (Glu 132, Glu 133 and Lys 136) form a hydrogen-bonding network. Here we show that site-specific mutants that increase local positive charge while maintaining this orienting network (Glu----Gln) have faster reaction rates and increased ionic-strength dependence, matching brownian dynamics simulations incorporating electrostatic terms. Increased positive charge alone is insufficient: one charge reversal (Glu----Lys) mutant is slower than the equivalent charge neutralization (Glu----Gln) mutant, showing that the newly introduced positive charge disrupts the orienting network. Thus, electrostatically facilitated diffusion rates can be increased by design, provided the detailed structural integrity of the active-site electrostatic network is maintained.     

脉冲辐解法研究双（二氧四胺）合铜（Ⅱ）催化歧化超氧负离子的动力学

The major function of superoxide dismutase(SOD)is to catalyze the dismutation of superoxide anion(·O^2-)and control intracellular and extracellular concentration of·O^2-. ·O^2- is the mediator of many diseases. Although SOD has been considered to be applied as a pharmaceutical     

双氧水对叶片延迟发光的影响

采用生物超微弱发光探测技术对不同浓度的双氧水(H2O2)胁迫下植物叶片的延迟发光、超氧物歧化酶(SOD)和脂氧合酶(LOX)活性等参数进行了测量和分析.结果表明:所有的浓度都使延迟发光衰减加快,随培养时间的增加,叶片的延迟发光衰减参数1/P的变化先比较缓慢,保持一段时间的相对稳定,然后明显下降;超氧物歧化酶(SOD)活性化整体上是下降的,脂氧合酶(LOX)活性先减小后增加.     

用光电子能谱研究金属锰、镁表面与甲醇、乙醇反应

用XPS和UPS法研究金属Mn、Mg表面与CH_3OH、C_2H_5OH的反应,室温下,ROH(R=CH_3,C_2H_5)以RO~-的形态吸附在Mg表面,Mn表面有较高的活性,ROH除以RO~-的形态被吸附外,部分还分解为O~(2-)和脱附的碳氢化合物,加热至600K时,Mn表面RO~-完全分解为O~(2-)和R,后者与表面氢结合后脱附,部分C_2H_5O~-中的碳成无定形碳并在～675K加氢脱附,ROH在氧化锰表面除以RO~-的形态被吸附外,在高于650K时还产生CH_2O_(a)、C_2H_4O_(a)等,这些物种在700K依然存在,氧化使锰表面断裂R—O和C—C键的活性降低而其脱氢活性仍然存在。     

锌对糖尿病大鼠抗氧化指标的影响

观察Zn^＋对四氧嘧啶诱发的糖尿病大鼠血液流变学的影响。按200mg／kg剂量腹腔内一次性注射四氧嘧啶（Alloxan）,建立大鼠糖尿病模型。应用Zn和二甲双胍进行为期4周的灌胃治疗,每周眼眶采血1次,对大鼠的红细胞超氧化物歧化酶（SOD）和血浆过氧化脂质产物（MDA）进行检测,4周后处死动物取肝脏检测肝脏SOD活性。结果表明10mg／kg·dZnSO4组、100mg／kg·d二甲双胍加5mg／kg·dZnSO4组、100mg／kg·d二甲双胍加10me,／kg·dZnSO4组可使糖尿病大鼠显著提高红细胞、肝脏SOD酶活性和降低血浆MDA含量（P〈0．05或P〈0．01）。Zn对实验性糖尿病大鼠提高SOD、减少MDA含量有明显作用,结合二甲双胍治疗效果更佳。     

超氧阴离子自由基(O_2~-)导致红细胞膜蛋白交联作用的机理探讨

用邻苯三酚在碱性条件下自氧化产生的超氧阴离子自由基(O_2_~-)处理人红细胞膜导致膜蛋白交联形成高分子聚合物(HMP)。用一定量的超氧化物歧化酶(SOD)预处理红细胞膜,HMP明显减少。用巯基抑制剂N-乙基马来酰胺(NEM)预处理红细胞膜,则HMP几乎消失。用特异性标记巯基的荧光探针N-(3-芘)马来酰胺(N-[3-P]NEM)来研究经不同浓度邻苯三酚处理的红细胞膜的荧光强度。结果表明,随着邻苯三酚浓度增高,荧光强度相应降低。上述结果提示,O_2~-可能主要是通过氧化巯基导致膜蛋白交联并形成HMP。     

金钱松种子贮藏过程中的生理生化特征研究

对不同含水率的金钱松种子在贮藏期间的发芽率、生活力以及各项生理生化指标的变化进行分析,结果表明:(1)金钱松种子临界含水率在3%～4%。含水率与发芽率、生活力以及POD活性之间存在显著负相关性,相关性大小排序为生活力、POD活性、发芽率。(2)金钱松种子可溶性蛋白质含量、粗脂肪含量、MDA含量、游离脯氨酸含量、SOD和POD活性与发芽率、生活力之间存在显著负相关性;各项指标与发芽率的相关性大小排序为SOD活性、MDA含量、可溶性蛋白质含量、游离脯氨酸含量、POD活性、粗脂肪含量,与种子生活力的相关性大小排序为SOD活性、POD活性、游离脯氨酸含量、粗脂肪含量、蛋白质含量、MDA含量。(3)O.2-含量虽然与金钱松种子发芽率、种子生活力之间的相关性不显著,但是与种子的可溶性糖和淀粉存在显著负相关性、与MDA含量之间存在显著正相关性。(4)金钱松种子可溶性糖和淀粉的含量与其他生理生化指标之间的相关性不显著。     

Superoxide dismutase as a target for the selective killing of cancer cells

Superoxide dismutases (SOD) are essential enzymes that eliminate superoxide radical (O2-) and thus protect cells from damage induced by free radicals. The active O2- production and low SOD activity in cancer cells may render the malignant cells highly dependent on SOD for survival and sensitive to inhibition of SOD. Here we report that certain oestrogen derivatives selectively kill human leukaemia cells but not normal lymphocytes. Using complementary DNA microarray and biochemical approaches, we identify SOD as a target of this drug action and show that chemical modifications at the 2-carbon (2-OH, 2-OCH3) of the derivatives are essential for SOD inhibition and for apoptosis induction. Inhibition of SOD causes accumulation of cellular O2- and leads to free-radical-mediated damage to mitochondrial membranes, the release of cytochrome c from mitochondria and apoptosis of the cancer cells. Our results indicate that targeting SOD may be a promising approach to the selective killing of cancer cells, and that mechanism-based combinations of SOD inhibitors with free-radical-producing agents may have clinical applications.     

Superoxide involvement in the bactericidal effects of negative air ions on Staphylococcus albus.

The physical nature of small air ions is well established and it is recognized that they can produce a variety of biological effects. However, in only a few instances have any underlying biochemical changes been detected. Theoretically, one can consider the hydrated superoxide radical anion (O2) (H2O)n with n congruent to 4-8 as a likely candidate for a biologically active species of negative air ion. The chemical and biological reactivity of superoxide is high and includes a leading role in bacterial killing caused by radiation, in which superoxide dismutase (SOD), an enzyme that catalyses the reaction: O2 + O2 +2H leads to H2O2 +O2 protected markedly. Other studies have also demonstrated the bactericidal effect of O2 (refs 9-11). Inasmuch as the bactericidal action of small negative air ions has been repeatedly confirmed, we decided to test for the involvement of O2 in this phenomenon by evaluating the protective effect of SOD. Our results show strong O2 involvement in negative air ion bacterial kill.     

不同光照条件对黄瓜幼苗的生理响应

探明不同光照条件对黄瓜幼苗的生理响应。本试验以"津春4号"黄瓜品种为材料,在黄瓜幼苗长至两叶一心时,分别置于不同光照下生长6 d,然后取第2片真叶测定相关指标。结果表明,在弱光下黄瓜叶片丙二醛(MDA)含量、超氧阴离子(O2.-)生成速率以及过氧化氢(H2O2)含量均有显著提高,过氧化氢酶(CAT)活力有所降低,抗坏血酸过氧化物酶(APX)、超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GPX)和谷胱甘肽还原酶(GR)活性有显著提高。     

红茶菌的制备工艺优化及抗衰老的实验研究

探讨红茶菌的制备工艺优化以及抗衰老作用.对传统设备工艺的改良以及通过建立果蝇的衰老模型,用本实验室研制的红茶菌喂养,通过测定果蝇的SOD,MDA含量及存活时间.红茶菌能显著增加果蝇SOD、降低MDA的含量,并且能显著延长果蝇存活时间.说明红茶菌具有明显的抗衰老作用.     

猪血超氧化物岐化酶的研究(Ⅰ) 猪血超氧化物岐化酶分子量的测定及稳定性的研究

猪血SOD是铜锌酶,分子量31600,对温度敏感,PH7.6～9.0稳定,PH6.0以下,PH12.0以上不稳定。具较强的抗胃蛋白酶和胰蛋白酶水解能力。     

牦牛血清转铁蛋白对人红细胞膜氧化损伤的保护作用

牦牛血清中分离纯化的转铁蛋白对人红细胞膜的抗氧化具有保护作用 .方法 :采用黄嘌呤 /黄嘌呤氧化酶、Fe2 + /H2 O2 两个体系产生的O·2 -、OH·对红细胞膜造成氧化损伤 ,通过丙二醛含量、超氧化物歧化酶和谷胱甘肽过氧化酶活性的测定研究牦牛转铁蛋白在抗氧化方面的作用与机制 .结果 :O·2 -和OH·可以造成红细胞膜丙二醛量的显著增加 ,超氧化物歧化酶和谷胱甘肽过氧化酶活性的下降 .当适量不同浓度牦牛血清转铁蛋白在黄嘌呤 /黄嘌呤氧化酶、Fe2 + /H2 O2 两个体系前处理可以抑制丙二醛的产生 ,保护红细胞膜免受丙二醛的氧化损伤并且使超氧化物歧化酶和谷胱甘肽过氧化酶活性升高 .提示 ,牦牛血清转铁蛋白对O·2 -和OH·自由基引起的氧化损伤有保护作用