Rapid tryptic peptide mapping of human serum albumin using DI-MS/MS^ALL

In recent decades, proteinic drugs, in particular monoclonal antibodies, are taking the leading role of small molecule drugs, and peptide mapping relying on liquid chromatography-tandem mass spectrometry (LC-MS/MS) is an emerging approach to substitute the role of a ligand-binding assay for the quality control of the proteinic drugs. However, such LC-MS/MS approaches extensively suffer from time-intensive measurements, leading to a limited throughput. To achieve accelerated measurements, here, the potential of DI-MS/MS^ALL towards tryptic peptide mapping was evaluated through comparing with well-defined LC-MS/MS means, and human serum albumin (HSA) was employed as the representative protein for applicability illustration. Among the 55 tryptic peptides theoretically suggested by Skyline software, 47 were successfully captured by DI-MS/MS^ALL through acquiring the desired MS² spectra, in comparison to 51 detected by LC-MS/MS. DI-MS/MS^ALL measurements merely took 5 min, which was dramatically superior to the LC-MS/MS assay. Noteworthily, different from fruitful multi-charged MS¹ signals for LC-MS/MS, most quasi-molecular ions received lower charged states. DI-MS/MS^ALL also possessed advantages such as lower solvent consumption and facile instrumentation; however, more sample was consumed. In conclusion, DI-MS/MS^ALL is eligible to act as an alternative analytical tool for LC-MS/MS towards the peptide mapping of proteinic drugs, particularly when a heavy measurement workload.