Using Tandem Mass Spectrometry for Amino Acid Sequence Analysis

The Tandem Mass Spectrometry (MS/MS) is the main technology currently used for the analysis of protein and peptide amino acid sequences. It allows researchers to determine the amino acid composition of small peptides and further identify the identity of proteins. Here are the basic steps of using MS/MS to determine amino acid sequences.

 

Sample Preparation

Protein samples are often first digested, with enzymes such as trypsin commonly used.This step produces peptides of a suitable size for mass spectrometry analysis.

 

Mass Spectrometry Analysis

1. In the first stage of MS (MS1), peptide ions are detected and their parent ion m/z recorded.

2. Some or all of the parent ions are selected for further fragmentation.

 

Tandem Mass Spectrometry Analysis (MS/MS)

1. In the collision cell, the parent ions interact with the collision gas and fragment to produce daughter ions.

2. The mass spectrum of the daughter ions is recorded.

3. By comparing the m/z values of the daughter ions, the amino acid sequence of the original peptide can be determined.

 

Data Processing and Peptide Identification

1. Mass spectrometry data processing software (such as Mascot, SEQUEST or MaxQuant) is used to analyse the MS/MS data.

2. The software matches the fragment pattern of the peptide with a known protein database to determine possible peptide amino acid sequences.

 

Protein Identification

1. Based on the matched peptides, the software can identify the proteins in the original sample.

2. The identification results can be evaluated with hypothesis testing and other statistical methods.

 

Extraction of Other Information

1. MS/MS data can also be used to identify protein post-translational modifications, such as phosphorylation, acetylation, etc.

2. Tandem mass spectrometry provides a powerful tool for proteomics, drug target identification, biomarker research and other fields.