CHARACTERIZATION OF LARGE, HETEROGENEOUS PROTEINS BY ELECTROSPRAY IONIZATION-MASS SPECTROMETRY

Characterization of heterogeneous proteins as large as 150,000 u was p erformed by a quadrupole mass spectrometer by using electrospray ioniz ation (ESI). We were able to determine not only the molecular weight, but the detailed heterogeneity for the large glycoproteins as well. Th e successful application was facilitated by the optimization of the in strument in the high mass-to-charge range up to m/z 4000, where the mu ltiply charged envelopes of the 150,000-u glycoproteins were found. Fo r the analysis of clinically important monoclonal antibodies mass spec tral data acquired by this method were consistent with the carbohydrat e analysis and were useful in resolving the monosaccharide data into g lycoform variations. In the case of the characterization of other larg e, heterogeneous proteins such as elongation factor 3 and bovine serum albumin, the quadrupole ESI mass spectrometer provided adequate mass resolution and high mass measurement accuracy to discern the modificat ion and degradation of the proteins. (C) 1996 American Society for Mas s Spectrometry.