Mass spectrometric strategies and their applications for molecular mass determination of recombinant therapeutic proteins.

Molecular weight determination of intact recombinant therapeutic proteins is a challenging analytical tool which furnishes valuable information not only for protein structure characterization but also to assess purity and heterogeneity. Up to now several mass spectrometric (MS) approaches have been reported for the measurement of monoisotopic or average masses of intact recombinant therapeutic protein. The choice of a suitable approach depends on several factors, among which are the sample complexity and homogeneity and the size of the target protein. MALDI-TOF, since it is rapid, simple and adaptable for automation has been found suitable for in-process monitoring quality of low/middle protein. High resolution MS such as Q-TOF, orbitrap and FT-ICR are excellent analytical tools for assessing protein heterogeneity and for structural characterization, in some cases without the need for proteolytic digestion and analysis of resulting products. High resolution techniques such as capillary electrophoresis (CE) and UPLC have been successfully coupled to high resolution MS analyzers in cases where the sample is complex and highly heterogeneous. The paper is a review of the most used and advanced MS strategies so far reported as well as of their applications in the biopharmaceutical field.