Intermolecular interactions, nucleation, and thermodynamics of crystallization of hemoglobin C.
Intermolecular interactions, nucleation, and thermodynamics of crystallization of hemoglobin C.
复制标题
血红蛋白 C 的分子间相互作用、成核和结晶热力学。
DOI：
10.1016/s0006-3495(02)75238-7
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发表时间：
2002
影响因子：
3.4
通讯作者：
Hirsch,RhodaElison
中科院分区：
文献类型：
--
作者：
Vekilov,PeterG;Feeling-Taylor,AngelaR;Petsev,DimiterN;Galkin,Oleg;Nagel,RonaldL;Hirsch,RhodaElison
突变的血红蛋白HbC（β6 Glu→Lys）在氧合（R）配体状态下，在CC和SC疾病患者的红细胞内形成晶体。静态和动态光散射表征的R-状态（CO）HbC，HbA，和HbS分子之间的相互作用在低离子强度的解决方案表明，静电是不重要的，相互作用是由溶液的离子的蛋白质的特异性结合为主。成核统计的显微镜观察和测定结果表明，HbC的晶体成核和生长的本地分子从溶液中的附件，并发的无定形相，球晶，和微纤维不是积木的晶体。使用一种新型的微型光闪烁技术，我们量化了对温度的强烈逆溶解度依赖性。HbC结晶的热力学分析产生了155 kJmol −1的高正焓，即，特定的相互作用有利于处于溶质状态的HbC分子。然后，HbC结晶是唯一可能的，因为610 Jmol − 1 K −1的巨大熵增益，可能源于每个蛋白质分子间接触-疏水相互作用释放多达10个水分子。因此，R状态HbC的更高结晶倾向归因于伴随HbCβ6突变的构象变化导致的疏水性增加。
The mutated hemoglobin HbC (β6 Glu→Lys), in the oxygenated (R) liganded state, forms crystals inside red blood cells of patients with CC and SC diseases. Static and dynamic light scattering characterization of the interactions between the R-state (CO) HbC, HbA, and HbS molecules in low-ionic-strength solutions showed that electrostatics is unimportant and that the interactions are dominated by the specific binding of solutions' ions to the proteins. Microscopic observations and determinations of the nucleation statistics showed that the crystals of HbC nucleate and grow by the attachment of native molecules from the solution and that concurrent amorphous phases, spherulites, and microfibers are not building blocks for the crystal. Using a novel miniaturized light-scintillation technique, we quantified a strong retrograde solubility dependence on temperature. Thermodynamic analyses of HbC crystallization yielded a high positive enthalpy of 155kJmol−1, i.e., the specific interactions favor HbC molecules in the solute state. Then, HbC crystallization is only possible because of the huge entropy gain of 610Jmol−1K−1, likely stemming from the release of up to 10 water molecules per protein intermolecular contact—hydrophobic interaction. Thus, the higher crystallization propensity of R-state HbC is attributable to increased hydrophobicity resulting from the conformational changes that accompany the HbCβ6 mutation.