Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ, UK.
Anal Chem. 2010 Nov 15;82(22):9557-65. doi: 10.1021/ac1022953. Epub 2010 Oct 27.
Collision cross sections in both helium and nitrogen gases were measured directly using a drift cell with RF ion confinement inserted within a quadrupole/ion mobility/time-of-flight hybrid mass spectrometer (Waters Synapt HDMS, Manchester, U.K.). Collision cross sections for a large set of denatured peptide, denatured protein, native-like protein, and native-like protein complex ions are reported here, forming a database of collision cross sections that spans over 2 orders of magnitude. The average effective density of the native-like ions is 0.6 g cm(-3), which is significantly lower than that for the solvent-excluded regions of proteins and suggests that these ions can retain significant memory of their solution-phase structures rather than collapse to globular structures. Because the measurements are acquired using an instrument that mimics the geometry of the commercial Synapt HDMS instrument, this database enables the determination of highly accurate collision cross sections from traveling-wave ion mobility data through the use of calibration standards with similar masses and mobilities. Errors in traveling-wave collision cross sections determined for native-like protein complexes calibrated using other native-like protein complexes are significantly less than those calibrated using denatured proteins. This database indicates that collision cross sections in both helium and nitrogen gases can be well-correlated for larger biomolecular ions, but non-correlated differences for smaller ions can be more significant. These results enable the generation of more accurate three-dimensional models of protein and other biomolecular complexes using gas-phase structural biology techniques.
在英国曼彻斯特的四极杆/离子淌度/飞行时间串联质谱仪（沃特世 Synapt HDMS）中，采用插入射频离子约束的漂移管，直接测量了氦气和氮气中的碰撞截面。本文报道了大量变性肽、变性蛋白、天然类似蛋白和天然类似蛋白复合物离子的碰撞截面，形成了跨越两个数量级的碰撞截面数据库。天然类似离子的平均有效密度为 0.6 g/cm³，显著低于蛋白质溶剂排除区域的密度，这表明这些离子可以保留其溶液相结构的显著记忆，而不是坍塌成球状结构。由于这些测量是使用模拟商业 Synapt HDMS 仪器几何形状的仪器进行的，因此，通过使用具有相似质量和淌度的校准标准品，该数据库可以从行波离子淌度数据中确定高度准确的碰撞截面。使用其他天然类似蛋白复合物校准的天然类似蛋白复合物的行波碰撞截面的误差明显小于使用变性蛋白校准的误差。该数据库表明，对于较大的生物分子离子，氦气和氮气中的碰撞截面可以很好地相关，但对于较小的离子，不相关的差异可能更为显著。这些结果使得使用气相结构生物学技术生成更准确的蛋白质和其他生物分子复合物的三维模型成为可能。
