Chemical Methods and Separations Group, Chemical Sciences Department, Battelle Pacific Northwest Laboratories, Battelle Boulevard, P8-19, P.O. Box 999, 99352, Richland, WA.
J Am Soc Mass Spectrom. 1994 Dec;5(12):1064-71. doi: 10.1016/1044-0305(94)85067-4.
Proton transfer reactions of multiply charged ions at high mass-to-charge ratios were explored with a low frequency quadrupole mass spectrometer. This instrument enabled a qualitative comparison of proton transfer reaction rates at low charge states for ions generated by electrospray ionization (ESI) from different solution conformations and for disulfide-linked versus disulfide-reduced protein ions. Proton transfer reactions that efficiently reduced the number of charges for ESI-generated ions to approximately the number of arginines in the polypeptide sequence were observed. No significant differences in gas-phase reaction rates were noted between different solution conformers. Differences in reaction rates between "native" and disulfide-reduced proteins were much smaller than those observed below m/z 2000 with lower proton affinity reagents or by using lower reagent concentrations. These smaller differences in reaction rates are thought to reflect the reduced electrostatic contributions from widely spaced charge sites and thus, the reduced sensitivi ty to an ion's three-dimensional structure or U compactness.
采用低频四极杆质谱仪研究了高质荷比下多电荷离子的质子转移反应。该仪器能够对通过电喷雾电离（ESI）从不同溶液构象产生的离子在低电荷态下的质子转移反应速率进行定性比较，以及对二硫键连接的和二硫键还原的蛋白质离子进行比较。观察到质子转移反应有效地将 ESI 产生的离子的电荷数减少到多肽序列中精氨酸数左右。不同溶液构象之间的气相反应速率没有明显差异。“天然”和二硫键还原蛋白之间的反应速率差异远小于使用较低质子亲和试剂或较低试剂浓度在 m/z 2000 以下观察到的差异。这种较小的反应速率差异被认为反映了电荷位点之间的静电贡献减少，从而降低了对离子三维结构或 U 紧凑性的敏感性。
