...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >Molecular dioxygen enters the active site of 12/15-lipoxygenase via dynamic oxygen access channels
【24h】

Molecular dioxygen enters the active site of 12/15-lipoxygenase via dynamic oxygen access channels

机译：分子双氧通过动态氧气通道进入12 / 15-脂加氧酶的活性位点

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Cells contain numerous enzymes that use molecular oxygen for their reactions. Often, their active sites are buried deeply inside the protein, which raises the question whether there are specific access channels guiding oxygen to the site of catalysis. Choosing 12/15-lipoxygenase as a typical example for such oxygen-dependent enzymes, we determined the oxygen distribution within the protein and defined potential routes for oxygen access. For this purpose, we have applied an integrated strategy of structural modeling, molecular dynamics simulations, site-directed mutagen-esis, and kinetic measurements. First, we computed the 3D free-energy distribution for oxygen, which led to identification of four oxygen channels in the protein. All channels connect the protein surface with a region of high oxygen affinity at the active site. This region is localized opposite to the nonheme iron providing a structural explanation for the reaction specificity of this lipoxy-genase isoform. The catalytically most relevant path can be obstructed by L367F exchange, which leads to a strongly increased Michaelis constant for oxygen. The blocking mechanism is explained in detail by reordering the hydrogen-bonding network of water molecules. Our results provide strong evidence that the main route for oxygen access to the active site of the enzyme follows a channel formed by transiently interconnected cavities whereby the opening and closure are governed by side chain dynamics.
机译：细胞含有大量使用分子氧进行反应的酶。通常，它们的活性位点深埋在蛋白质内部，这引发了一个问题，即是否存在将氧气引导至催化位点的特定通道。选择12 / 15-脂氧合酶作为此类依赖氧的酶的典型示例，我们确定了蛋白质内的氧分布并定义了氧进入的潜在途径。为此，我们应用了结构建模，分子动力学模拟，定点诱变-电离和动力学测量的集成策略。首先，我们计算了氧气的3D自由能分布，从而确定了蛋白质中的四个氧气通道。所有通道将蛋白表面与活性位点的高氧亲和力区域相连。该区域位于非血红素铁的对面，为该脂氧合酶同工型的反应特异性提供了结构上的解释。 L367F交换会阻碍最重要的催化路径，从而导致氧气的米氏常数大大增加。通过重新排列水分子的氢键网络，详细解释了阻断机理。我们的结果提供了有力的证据，表明氧到达酶活性位点的主要途径是由瞬时相互连接的空腔形成的通道，由此打开和闭合受侧链动力学控制。

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