MALDI TOF-MS analysis of high-mass impurities in immunoglobulin G solution using kinetic energy discrimination with superconducting detectors.

摘要

Time-of-flight mass spectrometry (TOF-MS) with matrix assisted laser desorption/ionization (MALDI) has become an essential spectrometry for a research field of bioscience. However, the mass limit of the conventional TOF-MS spectrometer frequently prevent us from measuring the mass values for large biomolecules without chemical or enzymatic digestion. Overcoming the circumstance, a TOF-MS instrument with superconducting tunnel junction (STJ) detectors (Super TOF-MS) were developed. The direct observation of the kinetic energy for each ion by Super TOF-MS leads to the two considerable capabilities: the observation of large proteins up to 1 M Dalton (Da) and the ionic charge-state discrimination of them, which are impossible with conventional ion detectors. In this paper, it is demonstrated that the Super TOF-MS is a powerful tool at performing a fragment analysis of, for example, immunoglobulin G (IgG) which is a large protein playing a key role in an immune system.