Mass spectral analysis of acetylated peptides: Implications in proteomics

• Published in: European Journal of Mass Spectrometry
• Main Authors: Chandra, Deepika, Gayathri, P, Vats, Mudita, Nagaraj, R, Ray, MK, Jagannadham, MV
• Format: Article in Journal/Newspaper
• Language: English
• Published: SAGE Publications 2019
• Subjects: Spectroscopy; Atomic and Molecular Physics, and Optics; General Medicine; Antarctic; Antarc*
• Online Access: http://dx.doi.org/10.1177/1469066719857564; http://journals.sagepub.com/doi/pdf/10.1177/1469066719857564; http://journals.sagepub.com/doi/full-xml/10.1177/1469066719857564

Sequence determination of peptides using mass spectrometry plays a crucial role in the bottom-up approaches for the identification of proteins. It is crucially important to minimise false detection and validate sequence of the peptides in order to correctly identify a protein. Chemical modification of peptides followed by mass spectrometry is an option for improving the spectral quality. In silico-derived tryptic peptides with different N-terminal amino acids were designed from human proteins and synthesized. The effect of acetylation on the fragmentation of peptides was studied. N-terminal acetylation of the tryptic peptides was shown to form b 1 -ions, improve the abundance and occurrence of b-ions. In some cases, the intensity and occurrence of some y-ions also varied. Thus, it is demonstrated that acetylation plays an important role in improving the de novo sequencing efficiency of the peptides. The acetylation method was extended to tryptic peptides generated from the proteome of an Antarctic bacterium Pseudomonas syringae Lz4W using the proteomics work flow and mass spectra of the peptides were analysed. Comparison of the MS/MS spectra of the acetylated and unacetylated peptides revealed that acetylation helped in improving the spectral quality and validated the peptide sequences. Using this method, 673 proteins of the 1070 proteins identified were validated.