Experimental and theoretical investigations on protein crystal nucleation are reviewed. Various experimental applications of the classical principle, which requires separation of the nucleation and growth stages of the crystallization process, are described. Temperature control is used most frequently, hypergravity and concentration changes being auxiliary techniques. Nucleation time-lags are measured by imposing temperature evoked supersaturation gradients. Application perspectives are revealed. Nucleation rates are measured according to the classical principle mentioned above, and energy barriers for crystal nucleation and numbers of molecules constituting the critical nuclei are calculated. Surprisingly, although requiring unusually high supersaturation, protein crystal nucleation occurs much more slowly than that with small molecule substances. On this basis novel notions are suggested for the elementary mechanism of protein crystal bond formation. Due to the selection of the crystalline bonding patches a successful collision between protein molecules, resulting in the formation of a crystalline connection, requires not only sufficiently close approach of the species, but also their proper spatial orientation. Imposing a rigid steric constraint, the latter requirement postpones the crystal nucleus formation. Besides, it was shown that cluster coalescence is not a factor, hampering the protein crystal nucleation. The comparison of the model predictions with experimental results proved that nucleation kinetics is governed by kinetic (not by energetic) factors.

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蛋白质晶体成核的动力学和密切机制

综述了蛋白质晶体成核的实验和理论研究。描述了需要分离结晶过程的成核和生长阶段的经典原理的各种实验应用。温度控制是最常用的，超重力和浓度变化是辅助技术。成核时间滞后是通过施加温度诱发的过饱和梯度来测量的。应用前景被揭示。根据上述经典原理测量成核速率，并计算晶体成核的能垒和构成临界核的分子数。令人惊讶的是，虽然需要异常高的过饱和度，但蛋白质晶体成核的速度比小分子物质要慢得多。在此基础上，提出了蛋白质晶体键形成的基本机制的新概念。由于选择了晶体键合补丁，蛋白质分子之间的成功碰撞导致晶体连接的形成，不仅需要物种足够接近，还需要它们适当的空间取向。强加刚性空间约束，后一要求推迟了晶核的形成。此外，还表明簇聚结不是阻碍蛋白质晶体成核的因素。模型预测与实验结果的比较证明成核动力学受动力学（而非能量）因素控制。由于选择了晶体键合补丁，蛋白质分子之间的成功碰撞导致晶体连接的形成，不仅需要物种足够接近，还需要它们适当的空间取向。强加刚性空间约束，后一要求推迟了晶核的形成。此外，还表明簇聚结不是阻碍蛋白质晶体成核的因素。模型预测与实验结果的比较证明成核动力学受动力学（而非能量）因素控制。由于选择了晶体键合补丁，蛋白质分子之间的成功碰撞导致晶体连接的形成，不仅需要物种足够接近，还需要它们适当的空间取向。强加刚性空间约束，后一要求推迟了晶核的形成。此外，还表明簇聚结不是阻碍蛋白质晶体成核的因素。模型预测与实验结果的比较证明成核动力学受动力学（而非能量）因素控制。以及它们适当的空间定位。强加刚性空间约束，后一要求推迟了晶核的形成。此外，还表明簇聚结不是阻碍蛋白质晶体成核的因素。模型预测与实验结果的比较证明成核动力学受动力学（而非能量）因素控制。以及它们适当的空间定位。强加刚性空间约束，后一要求推迟了晶核的形成。此外，还表明簇聚结不是阻碍蛋白质晶体成核的因素。模型预测与实验结果的比较证明成核动力学受动力学（而非能量）因素控制。