THE CRYSTAL-STRUCTURE OF HUMAN DEOXYHEMOGLOBIN AT 1.74A RESOLUTION
THE CRYSTAL-STRUCTURE OF HUMAN DEOXYHEMOGLOBIN AT 1.74A RESOLUTION
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DOI：
10.1016/0022-2836(84)90472-8
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发表时间：
1984-01-01
影响因子：
5.6
通讯作者：
FOURME, R
中科院分区：
文献类型：
--
作者：
FERMI, G;PERUTZ, MF;FOURME, R
人脱氧血红蛋白的结构在1.74埃处被精制。分辨率使用在室温下从同步加速器X射线源收集的胶片上的数据。晶体学R因子为16.0 °。原子位置的估计误差为0.1埃。总的来说，0.14埃。对于内部链段的主链原子，和0.05埃。对于Fe原子。分子间的接触对结构的影响进行了研究，这种接触只会导致高度局部化的扭曲，从分子的不对称程度，他们诱导的判断。Fe.sbd.N络合物的几何形状与脱氧肌红蛋白结构和5-配位模型化合物的几何形状非常相似。Fe与N（卟啉）的平均平面的距离为0.40（5）埃。和0.36（5）埃，分别在α.和β血红素，而相应的距离为+0.12（8）。和-0.11（8）.以HbO 2计; (F8)键长为2.12（4）。Fe·sbdN（卟啉）键长为2.06（12）埃;最后一个也是在良好的协议与扩展的X射线荧光光谱测量脱氧血红蛋白。血红素朝向近端侧呈圆顶状; N（卟啉）和C（卟啉）的平均平面之间的间隔为0.16（6）埃。和0.10（6）埃，分别在α.和β血红素在阿尔法。在血红素中，平均吡咯平面的法线均匀地向血红素中心倾斜Δ Px。3.degree.相对于血红素正常，有一个折叠。4.degree.血红素围绕着亚甲基碳之间的轴，亚甲基碳位于带有类似侧链的吡咯环之间。在. beta.血红素，没有这样的折叠，只有吡咯II和IV（那些被他的F8黯然失色）是明显倾斜，由。8度这些参数的独立性从施加在模型上的约束进行了验证，从一个结构与修改血红素几何形状的整个分子的无限制的细化。
The structure of human deoxyhemoglobin was refined at 1.74 .ANG. resolution using data collected on film at room temperature from a synchrotron X-ray source. The crystallographic R-factor is 16.0.degree.. The estimated error in atomic positions is 0.1 .ANG. overall, 0.14 .ANG. for main-chain atoms of internal segments, and 0.05 .ANG. for the Fe atoms. The effects of intermolecular contacts on the structure were investigated; such contacts cause only highly localized distortions, as judged from the degree of molecular asymmetry that they induce. The geometry of the Fe.sbd.N complex closely resembles that of the deoxymyoglobin structure and of the 5-coordinated model compound. The distance of the Fe from the mean plane of N(porphyrin) is 0.40(5) .ANG. and 0.36(5) .ANG., respectively, at the .alpha. and .beta. hemes, in contrast to the corresponding distance of +0.12(8) .ANG. and -0.11(8) .ANG. in HbO2; the Fe.sbd.N.epsilon.(F8) bond length is 2.12(4) .ANG. and the Fe.sbd.N(porphyrin) bond length is 2.06(l2) .ANG.; the last is also in good agreement with extended X-ray fluorescence spectroscopy measurements on deoxyhemoglobin. The hemes are domed toward the proximal side; the separation between the mean planes of N(porphyrin) and C(porphyrin) being 0.16(6) .ANG. and 0.10(6) .ANG., respectively, at the .alpha. and .beta. hemes. At the .alpha. hemes, the normals to the mean pyrrole planes are tilted uniformly toward the heme center, by .apprx. 3.degree. relative to the heme normal, and there is a folding of .apprx. 4.degree. of the heme about an axis running between the methene carbons that are betwen the pyrrole rings bearing like-type side-chains. At the .beta. hemes, there is no such folding, and only pyrroles II and IV (those eclipsed by His F8) are appreciably tilted, by .apprx. 8.degree.. The independence of these parameters from restraints imposed on the model was verified by unrestrained refinement of the entire molecule starting from a structure with modified heme geometry.