The development of ion mobility spectroscopy (IMS) and the appearance of tandem IMS-MS systems has led to a growing interest in using IMS for compound identification. IMS retention values are related to the average collision cross section (CCS) of the molecule, which can be accurately predicted based on a compound's 3D structure. For DrugBank 6.0 we used several published CCS predictors (Table 3), including AllCCS (14) and DeepCCS (15) to generate the CCS values for 11 417 small molecule drugs and 2852 metabolites. Most of these CCS predictors report errors of <3–4%. Using these predictors, a total of 34 251 predicted CCS values for drugs and 8556 predicted CCS for drug metabolites have been added to the DrugBank. All predicted CCS values have been entered in the ‘Predicted Spectral Properties’ subsection (under the ‘Properties’ field) of the relevant DrugCard. These CCS values have also been incorporated into DrugBank's new ‘LC–MS Search’ and ‘LC–MS/MS Search’ functions, which are described later.
