...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Acta crystallographica.Section D. Biological crystallography >Structure and catalytic mechanism of the evolutionarily unique bacterial chalcone isomerase
【24h】

Structure and catalytic mechanism of the evolutionarily unique bacterial chalcone isomerase

机译：的结构和催化机理独特的细菌进化查耳酮异构酶

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

Flavonoids represent a large class of secondary metabolites produced by plants. These polyphenolic compounds are well known for their antioxidative abilities, are antimicrobial phytoalexins responsible for flower pigmentation to attract pollinators and, in addition to other properties, are also specific bacterial regulators governing the expression of Rhizobium genes involved in root nodulation (Firmin et al., 1986[Firmin, J. L., Wilson, K. E., Rossen, L. & Johnston, A. W. B. (1986). Nature (London), 324, 90-92.]). The bacterial chalcone isomerase (CHI) from Eubacterium ramulus catalyses the first step in a flavanone-degradation pathway by ring opening of (2S)-naringenin to form naringenin chalcone. The structural biology and enzymology of plant CHIs have been well documented, whereas the existence of bacterial CHIs has only recently been elucidated. This first determination of the structure of a bacterial CHI provides detailed structural insights into the key step of the flavonoid-degradation pathway. The active site could be confirmed by co-crystallization with the substrate (2S)-naringenin. The stereochemistry of the proposed mechanism of the isomerase reaction was verified by specific 1H/2H isotope exchange observed by 1H NMR experiments and was further supported by mutagenesis studies. The active site is shielded by a flexible lid, the varying structure of which could be modelled in different states of the catalytic cycle using small-angle X-ray scattering data together with the crystallographic structures. Comparison of bacterial CHI with the plant enzyme from Medicago sativa reveals that they have unrelated folds, suggesting that the enzyme activity evolved convergently from different ancestor proteins. Despite the lack of any functional relationship, the tertiary structure of the bacterial CHI shows similarities to the ferredoxin-like fold of a chlorite dismutase and the stress-related protein SP1.
机译：类黄酮是一类大型次要的植物产生的代谢物。多酚化合物是众所周知的抗氧化能力,抗菌植物抗毒素负责花色素吸引传粉者,除了其他属性,也是特定的细菌监管机构管理根瘤菌的表达等的一家基因在根有节(公司dds倒闭。,的一家1986年[公司dds倒闭j . L。威尔逊,k . E。雷森,L . &约翰斯顿,a . w . b .(1986)。90 - 92年)。从真细菌小枝催化作用的第一步flavanone-degradation通路的戒指开放(2 s)柚苷配基柚苷配基查耳酮。植物的气已经有据可查的,而细菌的存在气最近才被阐明。细菌CHI提供了详细的结构结构的见解的关键一步flavonoid-degradation途径。可以通过co-crystallization确认了吗衬底(2 s)柚苷配基。建议的机制的异构酶反应是由特定的验证1 h / 2 h同位素交换1 h NMR实验和进一步观察到由诱变研究。由灵活的盖子,屏蔽不同吗可以模拟在不同的结构使用小角度的催化循环的状态x射线散射数据一起晶体结构。细菌气与Medicago植物酶发现它们马唐折叠无关,这表明酶活性进化从不同的祖先蛋白质聚合。尽管缺乏任何功能的关系,三级结构的细菌气显示相似的ferredoxin-like褶皱绿泥石歧化酶与压力相关的蛋白质SP1。

著录项

相似文献

  • 外文文献
  • 中文文献
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