Selected Reaction Monitoring Service

Overview

Selected Reaction Monitoring (SRM) is a targeted LC-MS/MS approach for quantitative measurement of selected peptide and protein targets.

During SRM analysis, predefined precursor-product ion transitions are monitored to selectively detect target peptides within complex biological samples. The precursor ions corresponding to selected peptides are isolated and fragmented, and specific fragment ions are measured as quantitative signals.

By combining precursor and fragment ion information, SRM provides high analytical specificity for targeted peptide measurement and generates reproducible quantitative data for focused proteomics studies.

Picotti, P. et al. Nat Methods. 2012.

Figure 1. The Principles of Selected Reaction Monitoring

SRM Service at MtoZ Biolabs

MtoZ Biolabs provides SRM-based targeted LC-MS/MS quantification services for selected peptide and protein targets across biological samples.

The service supports relative quantitative comparison between experimental groups and can incorporate isotope-labeled internal standards and calibration strategies for concentration measurement when required.

When This Service Is a Good Fit

SRM-based analysis is suitable for projects where:

• selected protein or peptide targets require quantitative measurement; 
• candidate molecules identified from discovery studies need further verification; 
• multiple biological samples require consistent targeted comparison; 
• focused quantitative analysis is required for specific molecular targets; 
• validation-oriented studies require reproducible measurement of selected analytes. 

For studies requiring broad proteome profiling before target selection, discovery-oriented approaches such as DIA or DDA proteomics may be considered prior to targeted SRM analysis.

Analysis Workflow

1. Target Peptide Selection

Target proteins and candidate peptide sequences are evaluated based on protein sequence information, peptide uniqueness, and quantitative suitability.

2. Sample Preparation

Samples undergo protein extraction, enzymatic digestion, and peptide preparation according to sample characteristics and analytical requirements.

3. LC-MS/MS Acquisition

Selected precursor-product ion transitions are monitored using targeted SRM acquisition to obtain quantitative peptide signals.

4. Quantitative Data Analysis

Chromatographic peaks and transition responses are processed for quantitative evaluation.

For projects requiring concentration measurement, isotope-labeled standards and calibration curves can be incorporated into the quantitative workflow.

Sample Submission Requirements

1. Supported Sample Types

SRM analysis can be applied to biological samples including tissues, cultured cells, biological fluids, and purified protein or peptide samples.

Final sample requirements depend on target abundance, sample complexity, and study design.

2. Storage and Shipping

Samples should be stored under appropriate frozen conditions and shipped on dry ice.

Samples should be prepared in LC-MS/MS-compatible conditions to support stable chromatographic separation and quantitative performance.

Applications

1. Biomarker Validation

SRM enables quantitative verification of candidate biomarkers identified from discovery studies, supporting validation across independent sample sets.

2. Disease Mechanism Studies

Targeted measurement of disease-associated proteins supports investigation of molecular changes involved in disease progression and biological regulation.

3. Drug Response Studies

SRM can be used to monitor changes in selected protein targets following drug treatment or experimental intervention.

4. Translational Research

Targeted LC-MS/MS assays support quantitative analysis of selected proteins or peptides in biological samples for translational research studies.

Service Advantages

1. High Target Specificity

SRM monitors predefined precursor-product ion transitions, providing high selectivity for target peptide detection in complex biological matrices.

2. Sensitive Targeted Measurement

Focused monitoring of selected transitions enables sensitive analysis of predefined peptide targets when appropriate assay conditions are established.

3. Reproducible Quantitative Performance

Optimized peptide selection, transition monitoring, and standardized workflows support consistent quantitative results across samples.

4. Flexible Quantification Strategies

SRM workflows can support relative comparison and isotope-standard-based quantitative analysis according to research objectives.

Deliverables

1. Target Peptide Information

Selected peptide sequences and related target information used for quantitative analysis.

2. SRM Transition Information

Precursor-product ion transition details and quantitative monitoring information.

3. Quantitative Results

Relative quantitative comparison or concentration calculation results where applicable.

4. Quality Assessment Results

Chromatographic peak evaluation and quantitative quality information.

5. Raw Mass Spectrometry Data

Original LC-MS/MS data files generated during analysis.

6. Final Report

Processed results and analytical summary.

FAQ

Q1. Is SRM the same as MRM?

SRM and MRM are closely related targeted mass spectrometry terms. In many applications, MRM refers to monitoring multiple SRM transitions simultaneously, particularly in triple quadrupole-based workflows.

Q2. Can SRM provide absolute quantification?

Yes. Absolute quantification can be performed using isotope-labeled internal standards and calibration curves when appropriate assay conditions are established.

Q3. Can SRM be combined with discovery proteomics?

Yes. Discovery approaches such as DIA or DDA can identify candidate proteins, while SRM can subsequently provide targeted quantitative verification of selected candidates.

Q4. How long does an SRM project usually take?

A typical project requires approximately 3-6 weeks, depending on target peptide selection, standard preparation, sample number, method development requirements, and instrument scheduling.

Contact Us

Selected Reaction Monitoring provides a targeted LC-MS/MS approach for sensitive and reproducible measurement of selected peptide and protein targets.

Contact MtoZ Biolabs with your target information, sample types, and research objectives to establish an appropriate SRM-based quantitative workflow.