Weik M, Kryger G, Schreurs A M, Bouma B, Silman I, Sussman J L, Gros P, Kroon J
Department of Crystal and Structural Chemistry, Bijvoet Center for Biomolecular Research, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.
Acta Crystallogr D Biol Crystallogr. 2001 Apr;57(Pt 4):566-73. doi: 10.1107/s0907444901001196.
The solvent behaviour of flash-cooled protein crystals was studied in the range 100--180 K by X-ray diffraction. If the solvent is within large channels it crystallizes at 155 K, as identified by a sharp change in the increase of unit-cell volume upon temperature increase. In contrast, if a similar amount of solvent is confined to narrow channels and/or individual cavities it does not crystallize in the studied temperature range. It is concluded that the solvent in large channels behaves similarly to bulk water, whereas when confined to narrow channels it is mainly protein-associated. The analogy with the behaviour of pure bulk water provides circumstantial evidence that only solvent in large channels undergoes a glass transition in the 100--180 K temperature range. These studies reveal that flash-cooled protein crystals are arrested in a metastable state up to at least 155 K, thus providing an upper temperature limit for their storage and handling. The results are pertinent to the development of rational crystal annealing procedures and to the study of temperature-dependent radiation damage to proteins. Furthermore, they suggest an experimental paradigm for studying the correlation between solvent behaviour, protein dynamics and protein function.
通过X射线衍射研究了骤冷蛋白质晶体在100 - 180 K范围内的溶剂行为。如果溶剂存在于大通道中，它会在155 K结晶，这可通过温度升高时晶胞体积增加的急剧变化来确定。相比之下，如果等量的溶剂被限制在狭窄通道和/或单个腔中，在研究的温度范围内它不会结晶。得出的结论是，大通道中的溶剂行为类似于大块水，而当被限制在狭窄通道中时，它主要与蛋白质结合。与纯大块水行为的类比提供了间接证据，表明只有大通道中的溶剂在100 - 180 K温度范围内经历玻璃化转变。这些研究表明，骤冷蛋白质晶体至少在155 K之前处于亚稳态，从而为其储存和处理提供了一个上限温度。这些结果与合理的晶体退火程序的开发以及蛋白质温度依赖性辐射损伤的研究相关。此外，它们提出了一种实验范式，用于研究溶剂行为、蛋白质动力学和蛋白质功能之间的相关性。
