How to use targeted proteomics to accurately detect low-abundance proteins?

In complex biological samples, the abundance of proteins can span up to a million-fold (10⁶). Many proteins with important biological functions, such as hormone receptors, transcription factors, signaling molecules, and early disease markers, often belong to the low-abundance category. Despite playing critical roles in life processes, traditional discovery proteomics methods (such as DDA) often struggle to stably detect these proteins due to their low abundance and complex background. Targeted Proteomics, through preset targets and highly selective scanning pathways, has become an important technique to solve the problem of detecting low-abundance proteins.

 

I. How Targeted Proteomics Overcomes the 'Dynamic Range Bottleneck'

1. Quantitative Advantages of MRM and PRM

Targeted proteomics employs preset target peptides and ion pairs, selectively collecting signals and performing multiple accumulations to improve signal-to-noise ratio and detection sensitivity.

(1) MRM (Multiple Reaction Monitoring) is based on triple quadrupole, offering high sensitivity and low background noise, suitable for high-background samples like serum and urine.

(2) PRM (Parallel Reaction Monitoring) is often paired with the Orbitrap platform and is superior to MRM in specificity, capable of identifying isobaric peptides and enhancing quantitative accuracy.

 

II. Key Technical Strategies for Precise Detection of Low-Abundance Proteins

1. Sample Preprocessing and Enrichment: Laying the 'Foundation'

(1) Immuno-enrichment (SISCAPA): Enrich specific peptides using antibodies to increase the target/background ratio.

(2) Desalting and High pH Reverse Phase Fractionation: Reduce complexity and prevent high-abundance proteins from masking signals.

At Biotree, targeted projects can be customized based on the characteristics of target proteins, implementing immunoaffinity chromatography and highly selective digestion processes to achieve precise coupling of sample processing and downstream mass spectrometry detection.

 

2. Optimizing Peptide Selection and Method Development

Select characteristic peptides that are free of post-translational modifications, easily ionized, and free of isobaric peptide interference. Fine-tune parameters such as collision energy, retention time window, and ion channel selection to achieve optimal monitoring conditions for each peptide.

 

III. From Relative to Absolute: Achieving High-Standard Quantification with Internal Standards

Targeted proteomics can not only perform relative quantification but also achieve absolute quantification through stable isotope-labeled peptides (SIS peptides). This strategy can provide accurate protein concentration information and is an important tool for translational clinical research.

 

Biotree supports the development of targeted quantification schemes based on SIS internal standards, suitable for research on various biomarkers such as tumors, metabolism, and immunity.

 

The precise detection of low-abundance proteins is not only a technical challenge but also a key step in advancing precision medicine. Targeted proteomics, with its high selectivity, high reproducibility, and strong translatability, provides solid support for biomarker development, pharmacodynamic evaluation, and clinical research. At Biotree, we focus on the 'subtle yet critical signals' in every sample, using professional platforms and optimized processes to help you explore every member in the 'deep sea' of the proteome.

 

Biotree Biotechnology - A Quality Service Provider in Biologic Characterization and Multi-Omics Mass Spectrometry Detection

 

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Targeted Proteomics