Label-free protein quantification technology
Label-free protein quantification is a method used for analyzing protein expression levels in biological samples without the need for any markers (such as radioactive isotopes, fluorescent labels, etc.) to label proteins. This technique typically relies on mass spectrometry (MS) technology to identify and quantify proteins by analyzing the mass of proteins or their digested products (peptides). Label-free protein quantification has a wide range of applications in biomedical research, disease diagnosis, drug development, and other fields.
Label-free protein quantification mainly includes the following methods:
1. MS-based comparative analysis:
Achieves relative quantification of proteins by comparing the mass spectrometric signal intensities of the same proteins or peptides in different samples. This method is straightforward but may be affected by sample processing, mass spectrometer performance, and other factors.
2. Label-assisted quantification:
Although the focus is on label-free techniques, it is worth mentioning label-assisted quantification techniques, such as isotope labeling, TMT (Tandem Mass Tag), etc., for comparison. These techniques achieve precise quantification by introducing labels during sample processing. Label-free techniques avoid the labeling process, thus reducing experimental complexity and cost.
3. Spectral counting:
A method that infers protein abundance based on the number of times a peptide is identified. The principle is that peptides identified multiple times in mass spectrometry correspond to proteins with higher abundance in the sample.
4. Extracted Ion Current (EIC):
Quantifies proteins by tracking changes in signal intensity of ions with specific mass-to-charge ratios (m/z) of particular peptides. This method requires a high level of expertise in mass spectrometry data analysis but can provide accurate quantification results.
5. SWATH-MS (Sequential Window Acquisition of All Theoretical Mass Spectra):
An advanced label-free quantification technique that achieves comprehensive quantitative analysis of almost all proteins in a sample by collecting data from a series of overlapping narrow-range mass spectrometry windows. SWATH-MS technology is gaining increasing attention in proteomics research for its high throughput and high reproducibility.
Label-free protein quantification overcomes some limitations of traditional labeling techniques, such as the complexity of sample processing, cost issues, and inconsistencies in labeling efficiency, providing an efficient and economical quantitative analysis tool for proteomics research. With the continuous advancement of mass spectrometry technology and data analysis methods, the application scope and accuracy of label-free protein quantification are continuously improving.
BiotechPack, A Biopharmaceutical Characterization and Multi-Omics Mass Spectrometry (MS) Services Provider
Related Services:
Quantitative Proteomics Analysis
Label-Free Based Quantitative Proteomics Analysis
Label-Based Protein Quantification Technologies - iTRAQ, TMT, SILAC
SILAC/Dimethyl Labeling Based Quantitative Proteomics Analysis
SWATH Quantitative Proteomics Service
2D-DIGE Quantitative Proteomics
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