Haemoglobin I from Lucina pectinata is a monomeric protein consisting of 142 amino acids. Its active site contains a peculiar arrangement of phenylalanine residues (PheB10, PheCD1 and PheE11) and a distal Gln at position E7. Active site mutations at positions B10, E7 and E11 were performed in deoxy haemoglobin I (HbI), followed by 10 ns molecular dynamic simulations. The results showed that the mutations induced changes in domains far from the active site producing more flexible structures than the native HbI. Distance analyses revealed that the heme pocket amino acids at positions E7 and B10 are extremely sensitive to any heme pocket residue mutation. The high flexibility observed by the E7 position suggests an important role in the ligand binding kinetics in ferrous HbI, while both positions play a major role in the ligand stabilisation processes. Furthermore, our results showed that E11Phe plays a pivotal role in protein stability.

中文翻译：

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刺槐血红蛋白 I 活性位点突变的影响：分子动力学研究

来自 Lucina pectinata 的血红蛋白 I 是一种由 142 个氨基酸组成的单体蛋白质。其活性位点包含苯丙氨酸残基（PheB10、PheCD1 和 PheE11）的特殊排列和 E7 位的远端 Gln。在脱氧血红蛋白 I (HbI) 中进行 B10、E7 和 E11 位置的活性位点突变，然后进行 10 ns 分子动力学模拟。结果表明，突变导致远离活性位点的结构域发生变化，产生比天然 HbI 更灵活的结构。距离分析表明，E7 和 B10 位的血红素口袋氨基酸对任何血红素口袋残基突变都极为敏感。E7 位置观察到的高度灵活性表明在亚铁 HbI 中的配体结合动力学中起重要作用，而这两个位置在配体稳定过程中都起着重要作用。此外，我们的结果表明 E11Phe 在蛋白质稳定性中起着关键作用。