Energy-structure correlation in metalloporphyrins and the control of oxygen binding by hemoglobin.
Energy-structure correlation in metalloporphyrins and the control of oxygen binding by hemoglobin.
复制标题
金属卟啉的能量-结构相关性和血红蛋白对氧结合的控制。
DOI：
10.1073/pnas.74.5.1789
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发表时间：
1977
影响因子：
11.1
通讯作者：
A. Warshel
中科院分区：
文献类型：
--
作者：
A. Warshel
通过将自洽力场推广到η电子分子的量子力学半经验方法计算了卟啉骨架对表面金属卟啉势能的贡献。该计算使得有可能将观察到的金属卟啉的结构与卟啉骨架的应变能相关联。研究发现，五配位血红素体系中金属离子的面外位移是由于卟啉空穴的尺寸受限以及轴向配体与血红素氮原子之间的“1-3”空间相互作用所致。血红蛋白活性中心的主要成分由组氨酸-血红素-氧系统模拟。该系统的能量表面提供了一个定量的解释血红蛋白的配体结合的控制。它表明，血红素作为一个隔膜，旨在提供同时结合的组氨酸和第六配体下的1-3相互作用的空间要求。血红蛋白的潜力表面的近端组氨酸和血红素平面之间的距离的依赖性进行评估的R和T状态，使用计算的血红素电位和所观察到的能量的血红素-血红素相互作用。
The contribution of the porphyrin skeleton to the potential energy surface metalloporphyrins is calculated by the semiempirical method of quantum mechanical extension of the consistent force field to eta electron molecules. This calculation makes it possible to correlate the observed structure of metalloporphyrins with the strain energy of the porphyrin skeleton. It is found that the out-of-plane metal displacement in pentacoordinate heme systems is due to both the restricted size of the porphyrin hole and the "1-3" steric interaction between the axial ligand and the heme nitrogens. The main components of the active site of hemoglobin are simulated by a histidine-heme-oxygen system. The energy surface of this system provides a quantitative explanation for the control of ligand binding by hemoglobin. It is shown that the heme acts as a diaphragm, designed to provide simultaneous binding to the histidine and the sixth ligand under the steric requirements of the 1-3 interactions. The dependence of the hemoglobin potential surface on the distance between the proximal histidine and the heme plane is evaluated for the R and T states, using the calculated heme potential and the observed energy of heme-heme interaction.