Dipole Alignment under Practical IMS Conditions

The preceding discussion (2.7.1) has clarified that only dipoles with substantial p can align under practical IMS conditions. In drift tube IMS, E typically equals 2-50 V/cm in low-pressure IMS/MS and MS/IMS/MS systems where P 15 Torr and 50-700 V/cm in high-pressure stand-alone IMS and IMS/MS with P 150-760 Torr . By Equation 2.78 at T= 300 K, pcrit 9 kD for even the highest E 700 V/cm and 60-600 kD for more common E 10-100 V/cm. DMA analyzers  

These values are minima that may be raised by the effect of rotational ion heating (2.7.2). For example, typical ions of medium-size proteins (e.g., ubiquitin and cytochrome c) generated by have To(O) 0.8-1.3 cm /(V s) or A fO) 

Dipole Moments Calculated for Native Conformations of 14 Common Polypeptides  

Protein/Peptide Organism PDB Access Code tires m (kDa) p(D) p/llres (1 

Liver alcohol dehydrogenase Equine 3BTO chain A 374 39.90 721 1.9 

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