Question

How are proteins identified by peptide sequencing in LC-MS/MS? How does the resolution of a mass spectropmeter affter the identification of proteins?

Answer 1

Answer

Peptide sequencing is the process of assigning amino acids from peptide fragment masses of a protein. This sequencing is based on mass and some amino acids have identical masses . So, accurate manual sequencing can be difficult. Therefore, it is necessary to utilize a sequence homology search application to work in tandem between a database search and peptide sequencing to address this inherent limitation. Identification of proteins can be fasten, provided they have already been documented in a database. An annotated peptide spectral library can also be used as a reference for protein identification. It offers the unique strength of reduced search space and increased specificity. The limitations include spectra not included in the library will not be identified, spectra collected from different types of mass spectrometers can have quite distinct features, and reference spectra in the library may contain noise peaks, which may lead to false positive identifications.

Resolution will give the better identification of proteins as it can give more separated and clear peak.