Two mainly used mass spectrometers are electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI), respectively. Mass spectrometry is a highly efficient method for the accurate mass determination and characterization of proteins. With current technology, it is fairly routine to obtain at least 20 to 25 residues of sequence from the N-terminus of the proteins and peptides.Ĭurrently, the most commonly used technique for protein sequence analysis is mass spectrometry. Though less efficient as compared with mass spectrometer, N-terminal Edman sequencing still has advantages for protein analysis that cannot readily be obtained by other analysis methods. Suppose the reactions are fully efficient, this method can sequence the whole amino acid from the N-terminal end. Protein sequence is therefore being analyzed in through a serious reaction of PITC addition, and cleavage of one PTH at each time for analysis. Subsequently, the derivatized terminal amino acid is removed by acid cleavage in a form of phenylthiohydantoin (PTH) derivative and a new α-amino group on the next amino acid is now available for the next round of reaction with PITC. In protein N-terminal sequence analysis, proteins are first modified with phenylisothiocyanate (PITC). Sequence Analysis of Peptides or ProteinsĬreative Proteomics provides N-terminal sequence analysis by both Edman and Mass spectrometry of therapeutic proteins, monoclonal antibodies and protein vaccines.
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