PRM Mass Spectrometry

Parallel Reaction Monitoring (PRM) is an ion monitoring technology based on high-resolution, high-precision mass spectrometry. The principle of this technology is similar to SRM/MRM, but it is more convenient in the development of absolute quantification of proteins and peptides. It is most suitable for quantifying multiple proteins in complex samples through attomolar level detection. PRM technology is a new type of protein validation technology without antibodies, which is used to validate relative quantitative proteomics data such as label free, iTRAQ, TMT, SILAC, or targeted quantitative analysis of target proteins in complex samples.

 

PRM is based on Q-Orbitrap as a representative quadrupole high-resolution mass spectrometry platform. Unlike SRM which executes one transition at a time, PRM performs a full scan of each transition of the precursor ion, i.e., parallel monitoring of all fragments of the precursor ion. First, PRM uses a quadrupole (Q1) to select precursor ions, usually with a window of m/z≤2; then, the precursor ions are fragmented in the collision chamber (Q2); finally, Orbitrap replaces Q3 to scan all product ions with high resolution and high accuracy. Therefore, PRM technology not only has the quantification ability of SRM/MRM targets, but also has qualitative ability. (1) The mass accuracy can reach the ppm level, which is more capable of eliminating background interference and false positives than SRM/MRM, effectively improving the detection limit and sensitivity in complex backgrounds; (2) Full scan of product ions, no need to select ion pairs and optimize fracture energy, easier to establish analysis; (3) Wider linear range: increased to 5-6 orders of magnitude.

 

Experimental Instruments

The basic principle of mass spectrometry is to use a mass spectrometer to ionize molecules in the sample and separate and detect them based on their mass/charge ratio (m/z). Its basic configuration includes:

 

1. Ion Source

A device that converts molecules in an analytical sample into ions. Common ionization methods include electron ionization, chemical ionization, laser desorption, etc.

 

2. Mass Analyzer

It separates and screens molecules based on their mass. Common mass analyzers include time-of-flight mass analyzers, quadrupole mass analyzers, ion traps, etc.

 

3. Detector

It measures the intensity and mass of the ion stream. Detectors can be photomultiplier tubes, electron multipliers, etc.

 

4. Data System

It records and processes mass spectrometry data, usually connected to a computer system for data analysis and interpretation.

 

Service Advantages

1. Ensure the sensitivity and specificity of quantification during high throughput detection.

2. Compared with SRM, it does not need parent ion/fragment ion pairs, only parent ion information is needed, making the experimental design simpler.

3. It can perform qualitative and quantitative analysis through secondary full scan, showing strong anti-interference ability and high resolution in complex backgrounds.

4. Synthetic standard peptides can be selectively added as needed, thus saving experimental costs.

5. PRM technology has excellent reproducibility, ensuring the stability of the results of repeated tests.