...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Biochemistry >Distal ligand reactivity and quaternary structure studies of proximally detached hemoglobins
【24h】

Distal ligand reactivity and quaternary structure studies of proximally detached hemoglobins

机译：近端血红蛋白的远端配体反应性和四级结构研究

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

The linkage between the proximal histidines and the proximal polypeptide in normal adult human hemoglobin (Hb A) has been proposed to play a major role in transmitting allosteric effects between oxygen binding sites [Perutz, M. F. (1970) Nature 228, 726—734]. Here we present circular dichroism (CD), 1H NMR, analytical ultracentrifugation, and stopped-flow kinetic data to better define the quaternary structure of hemoglobins in which the linkage between the proximal histidines and the polypeptide backbone has been broken [Barrick et al. Nat. Struct. Biol. 4, 78—83 (1997)] and to characterize the distal ligand binding properties of these proximally detached Hbs. CD spectroscopy indicates that rHb (ctH87G) and rHb (ctH87G/j3H92G) retain at least partial T-quaternary structure with distal ligand bound, whereas rHb (/3H92G) does not, consistent with ‘H NMR spectra. Analytical ultracentrifugation reveals significant tetramer dissociation in rilb (/3H92G) to be the likely cause of loss of T-state markers. These quaternary structure studies indicate that in distally liganded Hb, the T-state is compatible with proximal linkages in the /3- but not the ct-chains. ‘H NMR titrations of rHb (ctH87G) with n-butyl isocyanide demonstrate the ct-chains to be of high affinity as compared with the /3-chains. Comparing ligand association and dissociation rates between the rHb (o.H87G) variant with the T- and R-states of wild-type Hb A indicates that at the ct-chains, carbon monoxide affinity is modulated entirely by the proximal linkage, rather than from distal interactions. Some residual allostet-ic interactions may remain operative at the /3-chains of rHb (ctH87G).
机译：已提出正常成年人类血红蛋白（Hb A）中近端组氨酸和近端多肽之间的连接在氧结合位点之间的变构效应的传递中起主要作用[Perutz，M. F.（1970）Nature 228，726-734]。在这里，我们介绍了圆二色性（CD），1H NMR，分析超速离心和停流动力学数据，以更好地定义血红蛋白的四级结构，其中近端组氨酸和多肽骨架之间的连接被破坏了[Barrick等。纳特结构。生物学4，4,78-83（1997）]，并表征这些近端分离的Hbs的远端配体结合特性。 CD光谱表明，rHb（ctH87G）和rHb（ctH87G / j3H92G）至少保留了带有远端配体结合的部分T-四级结构，而rHb（/ 3H92G）却与'H NMR光谱不一致。分析性超速离心显示rilb（/ 3H92G）中大量四聚体解离可能是T状态标记丢失的可能原因。这些四元结构研究表明，在远端配体的Hb中，T状态与/ 3-链中的近端键兼容，但与ct链不兼容。 rHb（ctH87G）用正丁基异氰的1 H NMR滴定表明，与/ 3-链相比，ct链具有很高的亲和力。比较rHb（o.H87G）变体与野生型Hb A的T和R状态之间的配体缔合和解离速率，表明在ct链上，一氧化碳亲和力完全由近端键调节，而不是来自远端的互动。在rHb（ctH87G）的/ 3链上，一些残留的异位反应可能仍然有效。

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