Tandem mass spectrometry of multiply charged peptides and proteins.

摘要

In the past two years electrospray ionization (ESI), originally described by Dole and coworkers and reinvigorated by Fenn and coworkers, has received considerable attention as a soft ionization source for mass spectrometry. The ESI method produces intact, multiply charged, gas phase molecular ions of peptides and proteins from aqueous solution with mass to charge ratios (m/a) that are easily within the range of quadrupole mass spectrometers. Because of the possible additional structural information from collisionally induced dissociation (CID)/tandem mass spectrometry, multiply charged ions are likely candidates for examination by this technique, possibly producing all or significant portions of the amino acid sequence. Although the multiply charged ions give abundant fragmentation, it is still a question whether meaningful fragmentation can be efficiently produced by CID. It would also be anticipated that the charge state of the parent ion might significantly affect the daughter ion spectra both in ions observed and their intensities. Three peptides, mellitin, glucagon, and the synthetic T(sub 1) trypstic fragment of glucagon, and the protein cytochrome-c, have been investigated to examine these issues. 5 refs., 1 fig.