血红蛋白中的超快速CO动力学:阿迪亚巴特结合和重原子道化
Abdelkrim Benabbas1, Yuhan Sun1, Thomas L Poulos2
1Department of Physics and Center for Interdisciplinary Research on Complex Systems, Northeastern University , Boston, Massachusetts 02115, United States.
Journal of the American Chemical Society
|October 7, 2017
概括
碳一氧化物 (CO) 对ChCooA的重新结合是由于热因而形成的,与肌球蛋白和血红蛋白不同. 这项CO结合动力学研究揭示了低温时的血红蛋白动力学和量子道效应.
科学领域:
- 生物化学
- 物理化学
- 蛋白质动力学
背景情况:
- 一氧化碳激活蛋白 (ChCooA) 是一种参与CO代谢的血红蛋白.
- 了解连接蛋白与血红蛋白 (Myoglobin) 和血红蛋白 (Hb) 结合的动力学对于阐明它们的功能至关重要.
- 之前的研究通常假定CO与血红蛋白的结合是由于旋转选择规则而非adiabatic的.
研究的目的:
- 在广泛的温度范围内研究CO与ChCooA的超快速动力学.
- 将ChCooA中的CO再结合动力与Mb和Hb中的动力进行比较.
- 阐明控制二氧化碳结合机制的因素,包括附加性和性贡献.
主要方法:
- 超快速的运动测量CO重结成ChCooA.
- 从低温到室温的温度依赖的动力学研究.
- 实验数据与理论模型的比较,包括屏障分布和量子力学道.
主要成果:
- 对CO与ChCooA结合的阿雷尼乌斯前因子明显高 (∼10^11 s^-1) 比对Mb和Hb (∼10^9 s^-1),表明是一种基结合过程.
- 在所有温度下,CO与ChCooA的重新结合是无指数的,这归因于由血主导异质性引起的阻的分布.
- 温度依赖的动力学揭示了溶剂玻璃过渡 (Tg ≈ 180 K) 上方和下方的屏障分布的变化,而60 K以下的量子道变得显著.
结论:
- CO与ChCooA的结合是一种亚底离子过程,其中因子占主导地位.
- 血红异质性会产生重新结合障碍的分布,影响非指数动力学.
- 量子力学道在低温,特别是低于60K的温度下起作用.
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