Matrix-assisted laser desorption/ionization quadrupole Time-of-Flight Mass Spectrometry: An elegant tool for peptidomics

Abstract

A Matrix-assisted laser desorption/ionization hybrid quadrupole orthogonal acceleration time-of-flight mass spectrometer was employed to acquire neuropeptide mass spectra, directly from neuropeptide secreting tissue deposited on the sample target, in the presence of dihydroxybenzoic acid as matrix. The cockroach corpus cardiacum served as model neuroendocrine tissue. Twelve neuropeptide ion peaks, with mass-to-charge ratio values ranging between 800 and 3,000 Da were selected for tandem mass spectrometry. All peptides below 1,600 Da could be fully sequenced; tandem mass spectrometry analysis of the remaining (three) largest peptides resulted in (limited) sequence tags, which, also due to unavailability of an appropriate neuropeptide structure database, did not allow complete structure elucidation.

Enhancement of protein sensitivity for MALDI imaging mass spectrometry after chemical treatment of tissue sections

“…maging mass spectrometry (IMS) is becoming a key technology for the investigation of the molecular content of thin tissue sections in direct spatial correlation with the underlying histology [1][2][3][4]. An analysis by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) performed directly on a tissue section allows detection of a wide range of endogenous molecular species such as lipids [5,6], peptides [7][8][9][10], and proteins [1,3,11] as well as administered pharmaceuticals [12][13][14][15]. Typically, several hundred distinct protein mass signals are observed in a single analysis in a mass-to-charge (m/z) range up to 70,000, although the technology is capable of measurements exceeding 200,000 [16].…”

“…Current systems with enhanced electronics and improved acquisition systems are now equipped with solid-state Nd:YAG lasers (355 nm), functioning at repetition rates as high as 200 to 300 Hz [25,34]. IMS has also been successfully performed on other types of commercially available MS instruments, such as QqTOF, ion traps, and more recently Fourier transform ion cyclotron resonance (FT-ICR) systems [7,35,36]. Whereas early software programs for IMS data acquisition and visualization were written "in-house" [31,37], today almost every commercially available MALDI-based mass spectrometer is "imaging capable" and can be equipped with software for automated data acquisition, image reconstruction, and visualization.…”

Limitations of Mass Spectrometry-Based Peptidomic Approaches

“…T he development of mass spectrometry-based peptidomic techniques has revolutionized the field of peptides [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. Before development of peptidomics approaches, the detection of peptides was largely performed using radioimmunoassays [16].…”

“…For the identification of unknown peptides, it was previously necessary to extensively purify each peptide in order for Edman degradation sequencing to be effective. Mass spectrometry-based peptide discovery allowed for identification of peptides in complex mixtures [1][2][3][4][5][6][7][8][11][12][13][14][15]. Quantitative peptidomic approaches facilitated the relative quantification of peptides in mixtures, including both known and previously unknown peptides.…”

Peptides in the Brain: Mass Spectrometry–Based Measurement Approaches and Challenges

“…Other studies seek to measure the brain peptidome. The recently coined term peptidomics arose simultaneously from three separate groups in 2001 (14)(15)(16). Since then, numerous studies characterizing the subset of bioactive peptides related to the brain and other organs have appeared (17)(18)(19)(20)(21).…”