Principle of MRM/PRM Quantitative Proteomics

Quantitative proteomics is a critical component of modern biological research, primarily used to understand the functions of proteins within organisms, their interactions, and the changes they undergo in various diseases and physiological states. Multiple Reaction Monitoring (MRM) and Parallel Reaction Monitoring (PRM) are two essential quantitative analysis methods that efficiently and accurately detect and quantify proteins.

 

Principles of MRM

MRM is a mass spectrometry-based technique that selectively monitors specific precursor ions for quantitative analysis of target proteins. In MRM, proteins are first separated using liquid chromatography (LC), and then specific precursor ions are subjected to Collision-Induced Dissociation (CID) within the mass spectrometer, generating characteristic fragment ions. The key to MRM lies in simultaneously monitoring one or more precursor ions and their corresponding fragment ions, allowing for high sensitivity and specificity in protein quantification.

 

1. Mass Spectrometry Analysis Process

The first step in mass spectrometry analysis is Electrospray Ionization (ESI), which converts proteins in the sample into ions. These ions are then introduced into the mass spectrometer, where mass analysis occurs. Specific precursor ions are selected for further analysis in the collision cell, where they collide with an inert gas (e.g., argon), resulting in the generation of fragment ions. The mass-to-charge ratios (m/z) of these fragment ions are recorded and analyzed, enabling the quantification of target proteins.

 

2. Advantages and Disadvantages of MRM

The advantages of MRM include high sensitivity and specificity, allowing for accurate measurement of low-abundance proteins in complex biological samples. However, the drawbacks include a complex method development process, requiring optimization to ensure effective detection of specific ions.

 

Principles of PRM

PRM is another mass spectrometry-based quantitative method, often considered an extension of MRM. PRM directly monitors all fragment ions of precursor ions during mass spectrometry analysis rather than selecting just one specific fragment ion. This method allows for richer information acquisition within the same experiment and can improve the identification rate of target proteins.

 

1. Workflow of PRM

The workflow of PRM is similar to that of MRM, including sample separation, ionization, and mass spectrometry analysis. In PRM, all possible fragment ions are monitored within a certain time window, providing full-spectrum information for each precursor ion. This method enhances the comprehensiveness of protein identification while retaining quantitative capabilities.

 

2. Advantages and Limitations of PRM

The main advantage of PRM lies in its adaptability to complex samples and its comprehensive information acquisition. It can simultaneously detect multiple proteins and provide abundant quantitative data. However, PRM generally requires a longer analysis time and has higher data analysis demands, necessitating complex calculations and statistical analyses.

 

Both MRM and PRM methods exhibit broad application prospects in various fields, including fundamental biological research, disease diagnosis, and biomarker discovery. These technologies not only improve the accuracy of protein quantification but also help researchers delve into the complexity of biological systems.