通过Rubisco的CO2固定:对碳氧化,水化和C-C键裂解的关键步骤的计算剖析
H Mauser1, W A King, J E Gready
1Computational Molecular Biology and Drug Design Group, John Curtin School of Medical Research, Australian National University, Canberra ACT 0200, Australia.
Journal of the American Chemical Society
|November 1, 2001
概括
这项研究通过计算剖析了鲁比斯科的碳氧化机制,揭示了CO2的添加,水合和C-C键裂变是如何发生的. 它强调了和活性部位残留物在促进低激活能量的这些步骤中发挥的关键作用.
科学领域:
- 生物化学和分子生物学
- 计算化学计算化学
- 酶的机制 酶的机制
背景情况:
- 尽管进行了广泛的研究,但CO2固定酶Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) 的机制仍然不完全理解.
- 之前的研究集中在最初的化步骤上;随后的反应步骤需要进一步阐明.
- 活性位点离子和关键残留物的作用,特别是碳化Lys-201,对于Rubisco的功能至关重要.
研究的目的:
- 为了提供第一个完整的计算剖析的化反应后的化反应步骤.
- 调查中心离子和模拟活性点残留物在CO2固定中的作用.
- 阐明鲁比斯科活性部位中碳氧化,水化和C-C键裂变的机制.
主要方法:
- 采用密度函数理论 (DFT) 用B3LYP/6-31G(d) 层面进行几何优化.
- 使用B3LYP/6-311+G(2d,p) 单点能量计算计算的反应能量.
- 模拟了鲁比斯科活性部位和基质的片段,并结合了关键残留物和Mg离子协调的实验发现.
主要成果:
- 二氧化碳 (CO2) 添加直接发生,没有迈凯利斯复合物,然后在不同的步骤中对β-酸进行水合.
- 碳酸盐组作为化,水化和C-C键裂变的一般基质催化剂.
- C-C 键裂变是速度限制的步骤,由于在两个可能的水合物构成中具有特定的Mg 协调安排,其激活能量非常低 (2837 kcal mol(-1)).
结论:
- 这项研究提供了一个详细的计算模型,用于Rubisco的炭化,水化和C-C键裂解步骤.
- 活性位点残留物和离子协调对于稳定中间体和降低激活障碍,特别是C-C键裂变至关重要.
- 这些发现为优化Rubisco效率提供了见解,可能是通过酶工程或了解其在碳固定方面的局限性.
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