What Is the Specification for Protein Quantification Label?

Protein quantitative tags, such as Tandem Mass Tag (TMT) and Isobaric Tags for Relative and Absolute Quantitation (iTRAQ), are chemical labels used in mass spectrometry analysis. They allow the simultaneous quantitative comparison of protein expression in multiple samples. These tags are covalently attached to peptides in the sample and detected and quantified during mass spectrometry analysis by releasing a reporter ion.

 

Common types of protein quantitative tags include:

 

1. TMT Tags

Each TMT tag consists of three parts: a mass reporter group (with unique mass for detection and quantification), a balancer group (ensuring equal overall mass of all tags for isobaric mass spectrometry analysis), and a reactive group (reacts with the N-terminus or lysine side chain of peptides).

 

TMT tag specifications: TMT tags come in a variety of specifications, including TMT0, TMT2plex, TMT6plex, TMT10plex, TMT11plex, and the recently developed TMT16plex and TMTpro series. The number refers to the number of different samples that each tag set can label, for example, TMT10plex can be used to simultaneously compare 10 different samples.

 

2. iTRAQ Tags

iTRAQ tags also consist of a reporter group, a balancer group, and a reactive group. iTRAQ tags are attached to peptides by reacting with the amino group of the N-terminus and lysine side chain of peptides.

 

iTRAQ tag specifications: iTRAQ tags typically come in 4plex and 8plex specifications, allowing simultaneous quantitative analysis of four or eight samples.

 

Each type of tag has its specific specifications, such as reaction conditions, labeling efficiency, and sensitivity of mass spectrometry detection. These specifications are crucial for the design of experiments and the interpretation of data. For example, isotope tags need to have sufficient mass differences to be distinguished in spectra, while chemical tags need to have high labeling efficiency and stability.