Structural dynamics of myoglobin
Structural dynamics of myoglobin
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DOI：
10.1016/s0301-4622(00)00142-3
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发表时间：
2000-08-30
影响因子：
3.8
通讯作者：
Brunori, M
中科院分区：
文献类型：
--
作者：
Brunori, M
构象波动被用来解释小配体在蛋白质中的扩散是一种全球性现象的观察结果，如氧诱导的埋藏色氨酸荧光猝灭所表明的那样（例如）。在处理大型底物的酶中，在晶体结构中经常可以看到通往催化位点的通道；另一方面，在小球状蛋白中，尚不清楚在内部空间中发现的空腔是否通过定义扩散到活性位点的特定途径来控制其功能。本文就这一点进行了讨论，并报道了分子生物学中有关氢原子肌红蛋白的一些研究结果。由于与CO， O-2和NO加合物的光敏性使我们能够跟踪与配体通过基质迁移相关的事件，因此对肌红蛋白的构象松弛进行了广泛的研究。简要总结了激光光解、分子动力学模拟、x射线衍射等方法对wt型和突变型肌红蛋白中间态的研究结果。一种新的抹香鲸肌红蛋白三突变体（Mb-YQR）的光化学中间体的晶体学数据首次显示，光解的CO*位于一个xe结合腔中，从血红素组中移除。这些结果支持了蛋白质内部预先存在的“包装缺陷”在控制配体结合动力学（包括氧）中起主要作用，从而获得生存价值的观点。(C) 2000 Elsevier Science B.V.版权所有
Conformational fluctuations have been invoked to explain the observation that the diffusion of small ligands through a protein is a global phenomenon, as suggested (for example) by the oxygen induced fluorescence quenching of buried tryptophans. In enzymes processing large substrates, a channel to the catalytic site is often seen in the crystal structure; on the other hand in small globular proteins, it is not known if the cavities identified in the interior space are important in controlling their function by defining specific pathways in the diffusion to the active site. This point is addressed in this paper, which reports some relevant results obtained on myoglobin, the hydrogen atom of molecular biology. Protein conformational relaxations have been extensively investigated with myoglobin because the photosensivitity of the adduct with CO, O-2 and NO allows us to follow events related to the migration of the ligand through the matrix. Results obtained by laser photolysis, molecular dynamics simulations, X-ray diffraction of intermediate states of wt type and mutant myoglobins are briefly summarized. Crystallographic data on the photochemical intermediate of a new triple mutant of sperm whale myoglobin (Mb-YQR) show, for the first time, the photolyzed CO* sitting in one of the Xe-binding cavities, removed from the heme group. These results support the viewpoint that pre-existing 'packing defects' in the protein interior play a major role in controlling the dynamics of ligand binding, including oxygen, and thereby acquire a survival value. (C) 2000 Elsevier Science B.V. All rights reserved.