OBSERVATION OF LARGE SUBUNIT PROTEIN COMPLEXES BY ELECTROSPRAY-IONIZATION MASS-SPECTROMETRY

Mass spectrometry with electrospray ionization and a magnetic sector instrument was used to detect multiply charged molecules for the non-covalently bound dimeric subunit protein complexes of horse liver alcohol dehydrogenase (M(r) similar to 80 000) and the tetrameric complexes of yeast alcohol dehydrogenase (M(r) similar to 147 000) and rabbit muscle pyruvate kinase (M(r) similar to 232 000). Ions for the pyruvate kinase complex represent one of the largest intact protein complexes resolved by mass spectrometry. Solvation of the large gas phase complexes is indicated by the mass spectrometric results.