J. van der Greef

Sequence Informative Fragmentation in 252 Cf Plasma Desorption Mass Spectrometry

In the field of peptide chemistry plasma-desorption mass spectrometry (PDMS) is now fully accepted as a useful method for obtaining accurate molecular weight information on peptides up to about 25 kDa molecular weight. Furthermore it has given useful information in C-terminal sequence determination by analyzing the trunk peptide instead of the liberated amino acids [1]. In addition, the method is very useful in peptide mapping by the method introduced by Morris et al. [2] applying fast atom bombardment (FAB) mass spectrometry. In these experiments PDMS has mainly been used as a technique to obtain molecular weight information. Nevertheless in some reports the presence of sequence information has been shown in smaller peptides [3–6]. During peptide mapping of recombinant IL-3 however we obtained a spectrum of a 4600 Da peptide containing considerable sequence informative fragmentation.

Direct Neuropeptide Profiling of Single Neurons and Target Tissue by Matrix-Assisted Laser Desorption Ionization Mass Spectrometry

In the last decade, mass spectrometry has developed into an important analytical tool in the life sciences. This is due to the introduction of softionization techniques such as fast atom bombardment [1], electrospray ionization [2] and matrix-assisted laser desorption ionization [3, 4, 5, 6, 7], which have allowed routine mass measurements of peptides and proteins with high resolution and accuracy. The ability to make precise mass measurements for molecules of interest can solve many problems encountered in the life sciences that are difficult to address by other methods. Mass spectrometry may be used to check correctness of amino acid sequences based on data generated by cDNA cloning studies or Edman degradation of peptides and proteins. It may also serve to confirm the purity of the sample and to quantify the analytes. Mass spectrometry is equally effective in confirming and identifying chemical modifications of peptides with a predicted change in molecular weight, e. g., post-translational modifications such as N-terminal acetylation, C-terminal amidation and disulphide formation [8, 9, 10]. Moreover, the location and nature of carbohydrates, phosphates, lipid moieties, etc., which are important for the bioactivity of proteins, can be determined by mass spectrometry, often in conjunction with other methods such as chemical or enzymatic cleavages. In favourable conditions, noncovalent protein complexes can also be detected, which is important for enzyme-substrate studies, for example.