(DE-Pro, ABSciex) :fitted with a nitrogen laser (l=337 nm, 20 Hz) The time-of-flight
analyzer can be used in linear mode for high mass range (m/z>1000) and a
reflector mode for medium mass range (m/z 500- 6000) and high resolution. It is
mainly used in self-service by trained people. The same targets can be also
analyzed in MS/MS mode on the MALDI-TOF-TOF.
MALDI-TOF-TOF (4700 Proteomic Analyzer,
ABSciex): fitted with NdYAG laser (l=355 nm, 200 Hz). In linear mode, a
high mass detector (CovalX) allows the detection of high mass proteins (Mw up
to 106 Da). In reflector mode, high resolution (R~20 000) is
achieved in the range m/z<6000 (peptide mass fingerprint) for a moderate
number of peptides. A mode MS/MS with a collision cell (CID with high collision
energy 1 keV) allows fragmentation of selected ions to get sequence information
(protein identification, post-translationnal modifications, natural or
synthetic peptides…). An off-line coupling with nanoLC can be implemented by
means of an automatic spotter (ProBot, Dionex) using the MALDI sample plate.
(QTRAP LC/MS/MS System, ABSciex) : this instrument is a hybrid triple
quadrupole linear ion (range m/z < 1700). It can be coupled on line with a
liquid chromatography device (Ultimate 3000 Dionex) using medium flow rate
(µL/min). This mass spectrometer is mainly dedicated to the analysis of small
molecules (steroids, oligonucleotides….) in complex mixtures. MS and MS/MS
modes are used in routine analysis. MRM (Multiple Reaction Monitoring) is also
a very useful mode allowing the detection and quantitation of specific
compounds knowing their mass and that of fragments.
ESI-Orbitrap (LTQ-Orbitrap XL+ ETD, ThermoFisher
Scientific) :this hybrid mass spectrometer incorporates a linear ion trap
(LTQ) and the Orbitrap analyzer (range m/z <2000 in routine analysis). This
last one offers high resolution (R ~100 000), very accurate (~ppm) mass
measurement and high dynamic range. Nanospray ion sources are used in a static
or dynamic mode when coupled to nanoLC (a few tens of nL/min). This last mode
is the most appropriate one in proteomics for identification and characterization
of proteins from complex mixtures (digests of cellular extracts….). Exact mass
measurement for low mass compounds (m/z<400) is possible.
complementary fragmentation modes are available: CID low energy collision, HCD
high energy collision and ETD dissociation induced by electron transfer.
these mass spectrometers offer complementary performances (ionization,
fragmentation, robustness, resolution, precision, easy to handle sample…). All
are connected to data banks (NCBI, SwissProt…) through search engines (Mascot,