Control of Solvent Dynamics around the B12-Dependent Ethanolamine Ammonia-Lyase Enzyme in Frozen Aqueous Solution by Using Dimethyl Sulfoxide Modulation of Mesodomain Volume.
Control of Solvent Dynamics around the B12-Dependent Ethanolamine Ammonia-Lyase Enzyme in Frozen Aqueous Solution by Using Dimethyl Sulfoxide Modulation of Mesodomain Volume.
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DOI：
10.1021/acs.jpcb.9b02239
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发表时间：
2019-06
期刊：
影响因子：
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通讯作者：
Benjamen Nforneh;K. Warncke
中科院分区：
文献类型：
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作者：
Benjamen Nforneh;K. Warncke
在190-265 K温度范围内，利用顺磁氮氧自由基自旋探针TEMPOL的电子顺磁共振波谱研究了冷冻多晶水溶液中鼠伤寒沙门氏菌乙醇胺解氨酶（EAL）蛋白质周围的蛋白质相关结构域（PAD）和介观结构域（mesodomain）的温度依赖性结构和动力学.以0.5、2.0和4.0%v/v加入并在T ≤ 245 K下以最大冷冻浓度存在的二甲基亚砜（DMSO）改变了间隙含水DMSO介观结构域（Vmeso）相对于固定PAD体积（VPAD）的体积。Vmeso/ VPAD从0.8增加到6.0通过TEMPOL在两相之间的分配来量化。随着Vmeso/ VPAD的增加，介观结构域中的激活的TEMPOL旋转运动的Arrhenius参数保持均匀，而PAD中的TEMPOL参数显示出朝向介观结构域值的渐进变换（更高的迁移率）。PAD中的有序-无序转变（ODT）通过将TEMP 0 L从PAD排除到介观结构域中来检测。增加Vmeso/ VPAD（从215到200 K）的ODT T值系统地降低，PAD排序扭结的介观结构域的Arrhenius依赖。因此，在PAD-介孔结构域溶剂偶联中存在互惠性。结果被解释为冰边界约束的PAD溶剂的结构和动力学，这是通过介孔域传输，并在增加添加DMSO的介孔域体积减少的主导影响。通过改变添加的DMSO来系统地调谐PAD和介观结构域溶剂动力学是解决蛋白质-溶剂动力学耦合对EAL催化的贡献的一种精辟的方法。
The temperature-dependent structure and dynamics of two concentric solvent phases, the protein-associated domain (PAD) and the mesodomain, that surround the ethanolamine ammonia-lyase (EAL) protein from Salmonella typhimurium in frozen polycrystalline aqueous solution are addressed by using electron paramagnetic resonance spectroscopy of the paramagnetic nitroxide spin probe, TEMPOL, over the temperature ( T) range 190-265 K. Dimethyl sulfoxide (DMSO), added at 0.5, 2.0, and 4.0% v/v and present at the maximum freeze concentration at T ≤ 245 K, varies the volume of the interstitial aqueous DMSO mesodomain ( Vmeso) relative to a fixed PAD volume ( VPAD). The increase in Vmeso/ VPAD from 0.8 to 6.0 is quantified by the partitioning of TEMPOL between the two phases. As Vmeso/ VPAD is increased, the Arrhenius parameters for activated TEMPOL rotational motion in the mesodomain remain uniform, whereas the parameters for TEMPOL in the PAD show a progressive transformation toward the mesodomain values (higher mobility). An order-disorder transition (ODT) in the PAD is detected by the exclusion of TEMPOL from the PAD into the mesodomain. The ODT T value is systematically lowered by increased Vmeso/ VPAD (from 215 to 200 K), and PAD ordering kinks the mesodomain Arrhenius dependence. Thus there is reciprocity in PAD-mesodomain solvent coupling. The results are interpreted as a dominant influence of ice-boundary confinement on the PAD solvent structure and dynamics, which is transmitted through the mesodomain and which decreases with mesodomain volume at increased added DMSO. The systematic tuning of PAD and mesodomain solvent dynamics by the variation of added DMSO is an incisive approach for the resolution of contributions of protein-solvent dynamical coupling to EAL catalysis.