Large-Scale Structural Characterization of Drug and Drug-Like Compounds by High-Throughput Ion Mobility-Mass Spectrometry

Abstract

Ion mobility-mass spectrometry (IM-MS) can provide orthogonal information, i.e., m/z and collision cross section (CCS), for the identification of drugs and drug metabolites. However, only a small number of CCS values are available for drugs, which limits the use of CCS as an identification parameter and the assessment of structure–function relationships of drugs using IM-MS. Here, we report the development of a rapid workflow for the measurement of CCS values of a large number of drug or drug-like molecules in nitrogen on the widely available traveling wave IM-MS (TWIM-MS) platform. Using a combination of small molecule and polypeptide CCS calibrants, we successfully determined the nitrogen CCS values of 1425 drug or drug-like molecules in the MicroSource Discovery Systems’ Spectrum Collection using flow injection analysis of 384-well plates. Software was developed to streamline data extraction, processing, and calibration. We found that the overall drug collection covers a wide CCS range for the same mass, suggesting a large structural diversity of these drugs. However, individual drug classes appear to occupy a narrow and unique space in the CCS–mass 2D spectrum, suggesting a tight structure–function relationship for each class of drugs with a specific target. We observed bimodal distributions for several antibiotic species due to multiple protomers, including the known fluoroquinolone protomers and the new finding of cephalosporin protomers. Lastly, we demonstrated the utility of the high-throughput method and drug CCS database by quickly and confidently confirming the active component in a pharmaceutical product.

A structural examination and collision cross section database for over 500 metabolites and xenobiotics using drift tube ion mobility spectrometry

“… 26 – 28 , 46 The greatest amount of information available for metabolites is from TWIMS based CCS measurements. 44 , 47 – 51 However, the TWIMS CCS values were derived through calibration with molecules having known CCS values, such as polyalanine, which can introduce errors if the unknowns deviate from peptide-like structures or have different atom types ( i.e. Cl, Br, etc.…”

Recommendations for Reporting Ion Mobility Mass Spectrometry Measurements

“…(15) where c is a constant depending on the voltages used in the transfer optics (obtained from the MassLynx software; note that the resulting corrections are typically of the order of 100 μs in measured drift times of several ms, and uncertainties in the determination of c therefore have a small effect on the final measurement). The derived CCS′ versus t′ data are fitted using an empirically determined power law, 202 CCS′ = A t' N (16) its linearized version, 198 ln CCS' = ln A + N  ln t' (17) or a polynomial 67 CCS′ = A t' 2 + B t' + C…”

“…In 2006, the availability of IM-MS instrumentation from a major MS manufacturer marked the onset of a growing use of IM for the separation, identification, and structural characterization of analytes across diverse fields of science. These include: ionic clusters, [4][5][6][7][8] catalysts, 9,10 supramolecular complexes, [11][12][13][14] small organic molecules including drugs, 15,16 lipids 17,18 and other metabolites, [19][20][21] glycans, [22][23][24] peptides, [25][26][27] proteins, [28][29][30] synthetic polymers, [31][32][33] biomolecules 34,35 and biomolecular complexes [36][37][38] (native IM-MS). However, as IM-MS instruments now commercially available from different manufacturers operate according to different principles of ion mobility separation, 39 this introduces complexity-and potentially confusion-amongst practitioners and readers.…”

Mass spectrometry in drug metabolism and pharmacokinetics: Current trends and future perspectives

“…Alternatively, the CCS value of a product ion containing the biotransformation can be compared with that of the same product ion produced from authentic standards. The use of CCS databases might be another way forward since CCS measurements were shown to be very reproducible between different days and instruments if the same kind of ion mobility device and the same calibrant are applied …”

“…The use of CCS databases might be another way forward since CCS measurements were shown to be very reproducible between different days and instruments if the same kind of ion mobility device and the same calibrant are applied. 25 Another promising new technology is Infrared Ion Spectroscopy (IR-IS). 26 The coupling of MS with tunable IR laser spectroscopy allows IR spectra to be recorded for ions selected by MS by the detection of fragment ions generated at different IR wavelengths.…”