Medicharla V. Jagannadham
CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India
Title: Chemical modification of peptides followed by mass spectrometry: Implications in proteomics
Biography
Biography: Medicharla V. Jagannadham
Abstract
Determination of the sequence of the peptides, obtained from the proteolysis digestion of a protein, using mass spectrometry, is a crucial requirement in proteomics. Sequence of the tryptic peptides is usually obtained by database search or by de novo sequencing. The poor spectral quality and signal to noise ratio interferes in the analysis. Different types of algorithms (MASCOT, SEQUEST and others) are used for interpretation of the mass spectral data. When the database is not available, de novo sequencing is the only way to determine the sequence. The de novo sequence can be obtained by employing different methods of fragmentation (CID, HCD, ETD and ECD), getting information on their sequence and combining this information. Even with MS instruments with high mass accuracy and speed of analysis, the reproducibility of the mass spectrometry-based proteomics is being questioned from time to time. Acetylation of peptides improved the spectral quality, exhibited by an increase in b ion intensities in the MS/MS spectra, improves the efficiency of de novo sequence and helped in validating the database search results. It is a simple reaction, which can be carried out on complex protein digests as is required in proteomics. The identification of proteins from an Antarctic bacterium Pseudomonas syringae Lz4W and other species using this strategy will be discussed.