...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Chemical Reviews >Superoxide Dismutases and Superoxide Reductases
【24h】

Superoxide Dismutases and Superoxide Reductases

机译：超氧化物歧化酶和超氧化物还原酶

获取原文
   

获取外文期刊封面封底 >>

       
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Superoxide, O_2~(?-), is formed in all living organisms that come in contact with air, and, depending upon its biological context, it may act as a signaling agent, a toxic species, or a harmless intermediate that decomposes spontaneously. Its levels are limited in vivo by two different types of enzymes, superoxide reductase (SOR) and superoxide dismutase (SOD). Although superoxide has long been an important factor in evolution, it was not so when life first emerged on Earth at least 3.5 billion years ago. At that time, the early biosphere was highly reducing and lacking in any significant concentrations of dioxygen (O_2), very different from what it is today. Consequently, there was little or no O_2~(?-) and therefore no reason for SOR or SOD enzymes to evolve. Instead, the history of biological O_2~(?-) probably commences somewhere around 2.4 billion years ago, when the biosphere started to experience what has been termed the "Great Oxidation Event", a transformation driven by the increase in O_2 levels, formed by cyanobacteria as a product of oxygenic photosynthesis.1 The rise of O_2 on Earth caused a reshaping of existing metabolic pathways, and it triggered the development of new ones.2 Its appearance led to the formation of the so-called "reactive oxygen species" (ROS), for example, superoxide, hydrogen peroxide, and hydroxyl radical, and to a need for antioxidant enzymes and other antioxidant systems to protect against the growing levels of oxidative damage to living systems.
机译：O_2〜（α-）超氧化物在与空气接触的所有活生物体中形成，根据其生物学背景，它可能会作为信号剂，有毒物质或自发分解的无害中间体。其水平在体内受到两种不同类型的酶的限制，即超氧化物还原酶（SOR）和超氧化物歧化酶（SOD）。尽管超氧化物长期以来一直是进化的重要因素，但至少在35亿年前，生命才首次出现在地球上并非如此。当时，早期的生物圈正在高度还原，并且缺乏任何明显的双氧（O_2）浓度，与今天的状况截然不同。因此，几乎没有或没有O_2〜（β-），因此没有理由使SOR或SOD酶进化。相反，生物O_2〜（？-）的历史可能始于大约24亿年前，当时生物圈开始经历所谓的“大氧化事件”，这是由O_2水平升高驱动的转化，蓝细菌是氧气光合作用的产物。1地球上O_2的上升引起了现有代谢途径的重塑，并引发了新的代谢途径的发展。2其出现导致了所谓的“活性氧物种”（ ROS），例如超氧化物，过氧化氢和羟​​基自由基，以及对抗氧化剂酶和其他抗氧化剂体系的需求，以防止对生命系统的日益严重的氧化破坏。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号