T. Keough et al., Atmospheric pressure matrix-assisted laser desorption/ionization ion trap mass spectrometry of sulfonic acid derivatized tryptic peptides, RAP C MASS, 15(23), 2001, pp. 2227-2239
Atmospheric pressure matrix-assisted laser desorption/ionization (AP-MALDI)
and ion trap mass spectrometry have been used to study the fragmentation b
ehavior of native peptides and peptide derivatives prepared for de novo seq
uencing applications. Sulfonic acid derivatized peptides were observed to f
ragment more extensively and up to 28 times more efficiently than the corre
sponding native peptides. Tandem mass spectra of native peptides containing
aspartic or glutamic acids are dominated by cleavage on the C-terminal sid
e of the acidic residues. This significantly limits the amount of sequence
information that can be derived from those compounds. The MS/MS spectra of
native Cryptic peptides containing oxidized Met residues show extensive los
s of CH3SOH and little sequence-specific fragmentation. On the other hand,
the tandem mass spectra of derivatized peptides containing Asp, Glu and oxi
dized Met show much more uniform fragmentation along the peptide backbone.
The AP-MALDI tandem mass spectra of some derivatized peptides were shown to
be qualitatively very similar to the corresponding vacuum MALDI postsource
decay mass spectra, which were obtained on a reflector time-of-flight inst
rument. However, the ion trap mass spectrometer offers several advantages f
or peptide sequencing relative to current reflector time-of-flight instrume
nts including improved product ion mass measurement accuracy, improved prec
ursor ion selection and MSn. These latter capabilities were demonstrated wi
th solution digests of model proteins and with in-gel digests of 2D-gel sep
arated proteins. Copyright (C) 2001 John Wiley & Sons, Ltd.