Peptides plasma desorption mass spectrometry

R. A. Zubarev, V. D. Chivanov, P. Hakansson, B. U. R. Sundqvist, Peptide Sequencing by Partial Acid Hydrolysis and High Resolution Plasma Desorption Mass Spectrometry , Rapid Commun. Mass Spectrom. 1994, 8, 906-912. 

Further characterization of the remaining fraction in the low-sulfur keratin group in the ethanol-treated animals included analysis of the trypsin-released peptides by plasma desorption mass spectrometry. These results indicated the... 

Because C-terminal amides have often been reported in insect neuropeptides (8), a 33 residue C-terminal amide consistent with the sequence data was synthesized by solid-phase methods. The peptide was purified by HPLC and its structure confirmed by automated Edman degradation. Californium-252 time-of-flight plasma desorption mass spectrometry provided additional evidence for the structure via a very broad peak for the singly-charged molecular ion at m/z 3902-3906. Because the calculated MW of Hez-PBAN (3899.6, based on the most abundant ion in the isotope cluster) was seen to differ from that observed in the mass spectrum of the isolated native peptide by ca. 32, it was presumed that the native peptide had undergone oxidation of both its methionines to their respective sulfoxides during the course of its isolation and purification. 

New methods use combined HPLC/Mass spectrometry to identify modified amino acids. Purified recombinant human insulin-like growth factor separated into two peaks on reverse phase HPLC (Cl 8 column/acidified water) even though other methods indicated it was completely pure. Plasma desorption mass spectrometry of the individual peptides detected a single methionine sulfoxide molecule that was sufficient to decrease the hydrophobicity of the whole protein significantly. Most of the oxidation occurred when the secreted fusion protein was cleaved with hydroxylamine under not strictly anaerobic conditions, but about 5% occurred during die . coli fermentation. 

Cleavage of the peptide from the resin and side-chain deprotection were carried out by treatment of the peptidyl resin with TFA/TlS/water (90 5 5) for 2.5 h. The crude peptide was analysed by HPLC (Figure 2d) and plasma desorption-mass spectrometry (PD-MS) [expected MH 1139.2, found 1139.1]. 

Plasma Desorption Mass Spectrometry of Peptides and Proteins... 

Klarskov, K., Breddam, K., and Roepstorff, P. (1989) C-terminal sequence determination of peptides degraded with carboxypeptidases of different specificity and analyzed by Cf plasma desorption mass spectrometry. Anal. Biochem. 180, 28-37. 

Nielsen, P. F., Klarskov, K., Hojrup, P., and Roepstorff, P. (1988) Optimization of sample preparation for plasma desorption mass spectrometry of peptides and proteins. Biomed. Environm. Mass Spectrom. IS, 305-310. 

Roepstorff, P. (1989) Plasma desorption mass spectrometry of peptides and proteins. Acc. Chem. Res. 22, 421-427. 

Roepstorff P, Nielsen PF, Klarskov K, Hojrup P. Applications of plasma desorption mass spectrometry in peptide and protein chemistry. Biomed Environ Mass Spectrom. 1988 16 9-18. 

Much of the current interest in time-of-flight mass spectrometers is driven by instruments which desorb nonvolatile molecules (particularly peptides and other biological molecules) from surfaces. These methods include plasma desorption mass spectrometry (PDMS), laser desorption (LD), and matrix-assisted laser desorp-tion/ionization (MALDI), and they greatly simplify the design of time-of-flight mass spectrometers, since they effectively eliminate both the time- and spatial-distribution problems. 

In Chapter 4 we described a number of examples using plasma desorption mass spectrometry to map enzymatic digests. However, continuing an earlier example from this chapter, plasma desorption mass spectrometric analysis of amyloid peptides (PAi 4o and PAi 2) digested with pepsin resulted in peaks at m/z 561.1,613.1, 746.1, 1492.2, 1999.2, 2199.9, and 2315.2 that could be assigned to the peptide fragments ... 

The cross-reactivity between various fruits and different pollen allergens is a well-known fact and has already been studied in the 80s of the last century [19,20] using radioallergosorhent tests (RASTs). One of the first pollen allergens characterized by mass spectrometry is betv 1, the major birch pollen allergen [21]. Plasma desorption mass spectrometry (PD-MS) was used to confirm the primary structures of the intact purified protein, of all potential isoforms and some selected proteolytic peptides and to invesfigate any possible posttranslational modifications. 

Plasma desorption mass spectrometry has been employed in only a few laboratories for peptide identification. Nevertheless, the techniques can yield useful structural information [see ref. (1), p. 1209]. For example, in the positive Cf spectrum of the 31-residue peptide P-endorphin, an [M -h Na] ion at m/z 3487 was readily identifiable. In a more recent... 

Until 1988, the mass spectrometric analysis of peptides and proteins was difficult. Some results were achieved using (continuous-flow) fast-atom bombardment (FAB) and Cf plasma desorption. The major breakthrough in the characterization of proteins by mass spectrometry (MS) is due to the introduction of matrix-assisted laser desorption/ionization (MALDI) and electrospray ionization (ESI) in 1988. Currently, peptides and proteins form the compound class most intensively studied by MS. This is primarily due to the prominent role ESI-MS and MALDI-MS play in the field of proteomics. 

Early in the history of mass spectrometry (MS), large biomolecules were not analyzed because efficient methods to transport these molecules into the gas phase were unknown. Degradation typically occurred during vaporization of these nonvolatile molecules so that electron ionization of the intact molecular ion was not possible. Ionization by fast atom bombardment (FAB), field desorption (FD), secondary ionization mass spectrometry (SIMS), and plasma desorption (PD)" from the radioactive decay of Cf finally made the ionization and analysis of peptides possible. These latter techniques, although still used today, are not as popular as electrospray... 

In the past decade, mass spectrometry (MS) has become the method of choice for quality control of synthetic peptides. Historically, plasma desorption (PD) and fast atom bombardment (FAB) were the first ionization methods used for the mass analysis of nonderivatized peptides. More recently, electrospray ionization (ESI) MS and matrix-assisted laser desorption ionization (MALDI) MS have found widespread utility for peptide analysis. Both of the latter methods yield protonated molecules and, thus, provide direct molecular weight information. As will be covered later, ESI can be employed with a variety of mass analyzers, including quadrupole, magnetic sector, ion trap, and time-of-flight (TOF) analyzers. On the other hand,... 

Several mass spectrometric techniques including fast atom bombardment (FAB), plasma desorption (PD), matrix-assisted laser desorption/ionization (MALDI), and electrospray (ES) mass spectrometry (MS) are presently available for the analysis of peptides and proteins (Roepstorff and Richter, 1992). Of these techniques, mainly PDMS has gained footing in protein laboratories because the instrumentation is relatively cheap and simple to operate and because, taking advantage of a nitrocellulose matrix, it is compatible with most procedures in protein chemistry (Cotter, 1988 Roepstorff, 1989). Provided that the proper care is taken in the sample preparation procedure most peptides and small proteins (up to 10 kDa) are on a routine basis amenable to analysis by PDMS. Molecular mass information can be obtained with an accuracy of 0.1% or better. Structural information can be gained by application of successive biochemical or chemical procedures to the sample. 

See also Biochemical Applications of Mass MS-MS and MS Organometallics Studied Using Spectrometry Fragmentation in Mass Spectrometry Mass Spectrometry Peptides and Proteins Studied Ion Energetics in Mass Spectrometry Ionization The- Using Mass Spectrometry Plasma Desorption loniza-ory IR Spectroscopy Sample Preparation Methods tion in Mass Spectrometry Spectroscopy of Ions. 

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