PRM Targeted Quantitative Proteomics

Parallel Reaction Monitoring (PRM) is an ion monitoring technique based on high-resolution and high-precision mass spectrometry, used for the absolute quantification of proteins or peptides. PRM is well-suited for quantifying multiple low-abundance proteins in complex samples. PRM is based on a quadrupole high-resolution mass spectrometry platform, typically represented by the Q-Orbitrap. Unlike SRM, which scans only one parent-daughter ion pair at a time, PRM scans all parent-daughter ion pairs of the parent ion, i.e., it monitors all fragment ions of the parent ion in parallel. First, PRM uses a quadrupole (Q1) to select the parent ion, typically with a selection window of m/z ≤ 2; then, the parent ion fragments in the collision cell (Q2); finally, the Orbitrap, replacing Q3, scans all fragment ions with high resolution and high precision. Therefore, PRM technology not only possesses the targeted quantitative analysis capabilities of SRM/MRM but also qualitative functions.

(1) The quality accuracy can reach the ppm level, and its ability to distinguish between background interference and false positives is better than SRM/MRM, effectively improving the detection limit and sensitivity in complex backgrounds;

(2) Full scan of daughter ions, no need to select ion pairs and optimize fragmentation energy, making it easy to establish analytical methods;

(3) Wide linear range, which can increase by 5-6 orders of magnitude.

PRM Applications

After obtaining numerous differentially expressed proteins through various high-throughput relative quantitative analyses such as TMT, label-free, and DIA, these differentially expressed proteins require further validation to obtain more accurate information on the relative abundance of protein expression. This is typically confirmed using methods such as Western blotting and ELISA. However, mass spectrometry (MS) offers targeted quantitative analysis of target proteins with accuracy and sensitivity comparable to Western blotting, but with higher throughput, validating 1-100 proteins at a time, and at a lower cost.

• Validation of differentially expressed proteins screened by proteomics (TMT, DIA, etc.)
• Absolute quantification of proteins or peptides
• Quantification of disease markers for establishing diagnostic models
• Quantification of phosphorylated/methylated proteins
• Quantitative analysis of signaling pathways