Tarver Crissy L, Yuan Qunying, Pusey Marc L
Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA.
Department of Biological and Environmental Science, Alabama A&M University, Normal, AL 35762, USA.
Crystals (Basel). 2021 Oct;11(10). doi: 10.3390/cryst11101166. Epub 2021 Sep 24.
Among its attributes, the mythical philosopher's stone is supposedly capable of turning base metals to gold or silver. In an analogous fashion, we are finding that protein crystallization optimization using ionic liquids (ILs) often results in the conversion of base protein precipitate to crystals. Recombinant inorganic pyrophosphatases (8 of the 11 proteins) from pathogenic bacteria as well as several other proteins were tested for optimization by 23 ILs, plus a dHO control, at IL concentrations of 0.1, 0.2, and 0.4 M. The ILs were used as additives, and all proteins were crystallized in the presence of at least one IL. For 9 of the 11 proteins, precipitation conditions were converted to crystals with at least one IL. The ILs could be ranked in order of effectiveness, and it was found that ~83% of the precipitation-derived crystallization conditions could be obtained with a suite of just eight ILs, with the top two ILs accounting for ~50% of the hits. Structural trends were found in the effectiveness of the ILs, with shorter-alkyl-chain ILs being more effective. The two top ILs, accounting for ~50% of the unique crystallization results, were choline dihydrogen phosphate and 1-butyl-3-methylimidazolium tetrafluoroborate. Curiously, however, a butyl group was present on the cation of four of the top eight ILs.
在其诸多特性中，传说中的点金石据说能够将贱金属转化为金或银。以类似的方式，我们发现使用离子液体（ILs）优化蛋白质结晶常常会使基础蛋白质沉淀转化为晶体。对来自致病细菌的重组无机焦磷酸酶（11种蛋白质中的8种）以及其他几种蛋白质，用23种离子液体加上一个双水相（dHO）对照，在离子液体浓度为0.1、0.2和0.4 M的条件下进行优化测试。离子液体用作添加剂，所有蛋白质都在至少一种离子液体存在的情况下进行结晶。对于11种蛋白质中的9种，沉淀条件通过至少一种离子液体转化为了晶体。离子液体可以按有效性排序，并且发现仅用一组8种离子液体就能获得约83%的由沉淀衍生的结晶条件，其中效果最佳的两种离子液体占成功案例的约50%。在离子液体的有效性方面发现了结构趋势，较短烷基链的离子液体更有效。占独特结晶结果约50%的两种效果最佳的离子液体是磷酸二氢胆碱和四氟硼酸1-丁基-3-甲基咪唑鎓。然而，奇怪的是，在前八大离子液体中，有四种的阳离子上存在丁基。
