Protein and Peptide Molecular Weight Determination Service

Protein and peptide molecular weight determination plays a critical role in both basic and applied research. It serves as a key indicator for verifying molecular identity, structural integrity, and purity, while also providing essential information for studying post-translational modifications, aggregation states, and complex formation. Accurate molecular weight data help confirm whether protein expression and modifications meet expectations, reveal function-related structural changes, and provide reliable support in biopharmaceutical development and quality control. Among the commonly used methods, mass spectrometry is central, with MALDI-TOF MS and ESI-MS widely applied due to their high sensitivity and resolution. In addition, SEC-MALS and ultracentrifugation are frequently used to analyze absolute molecular weight and aggregation states of proteins in solution, offering multi-dimensional insights for protein science research.

 

MtoZ Biolabs’ Protein and Peptide Molecular Weight Determination Service leverages high-precision mass spectrometry and multi-angle light scattering technologies to deliver comprehensive and highly reliable molecular weight analysis solutions. We utilize MALDI-TOF MS and ESI-MS for the rapid and accurate identification of precise molecular weights, while SEC-MALS enables absolute molecular weight and aggregation state determination directly in solution under near-native conditions. From recombinant proteins purified from expression systems, native proteins, peptide antigens, enzyme digestion products, to complex protein assemblies, we provide high-resolution quality confirmation and state evaluation to support protein research, drug development, and quality control.

 

Services at MtoZ Biolabs

1. MALDI TOF Molecular Weight Identification Service

MALDI TOF MS is a highly efficient method widely used for protein and peptide molecular weight determination. The principle involves mixing the sample with an organic matrix and subjecting it to laser irradiation, during which the matrix absorbs the energy and transfers it to the analyte, resulting in soft ionization of proteins or peptides into charged ions. These ions are then accelerated into a flight tube, where their time-of-flight correlates with their mass-to-charge ratio, enabling precise molecular weight calculation. The key advantages of MALDI-TOF include excellent compatibility with large biomolecules, gentle ionization that preserves molecular integrity, low sample requirements, high sensitivity, and a broad detection range from a few hundred daltons to hundreds of kilodaltons. Furthermore, its high-throughput capability allows rapid analysis of large numbers of samples in a short time.

 



Carrera, M. et al. Humana, Press. 2021.

Figure 1. Workflow of Protein and Peptide Molecular Weight Determination by MALDI-TOF MS

 

2. High-Resolution LC-MS Molecular Weight Identification Service

High-resolution LC-MS is a highly efficient method for molecular weight determination, particularly suitable for complex mixtures, intact proteins, peptides, and samples with post-translational modifications. The process combines liquid chromatography to reduce sample complexity with electrospray ionization to generate multiply charged ions, followed by precise mass measurement using high-resolution instruments such as Orbitrap or FTICR. Its main advantages include outstanding mass accuracy and resolution, allowing clear discrimination of closely related molecular species and detection of subtle modifications or structural variations. In addition, it features high sensitivity, broad dynamic range, and low sample requirements, making it well-suited for a wide range of molecular weight analysis in scientific research and biopharmaceutical studies.

 

3. SEC-MALS Molecular Weight Determination Service

SEC-MALS is a powerful technique widely applied in protein and peptide molecular weight determination. It works by first separating samples according to size via size exclusion chromatography, followed by measuring light scattering intensity at multiple angles to determine molecular weight. Because scattering intensity is directly proportional to molecular weight and concentration, combining MALS with concentration detectors such as RI (refractive index) or UV enables accurate determination of absolute molecular weight. SEC-MALS not only measures the precise molecular weight of protein or peptide monomers, but also provides distribution information for aggregates, oligomers, and complexes, while revealing sample homogeneity and aggregation states. Conducted in solution, SEC-MALS maintains proteins and peptides in their near-native conformations, making it particularly suitable for studying folding, interactions, aggregation behavior, as well as biopharmaceutical quality control and stability evaluation.

 



Figure 2. Workflow of Protein and Peptide Molecular Weight Determination by SEC-MALS

 

Service Advantages

1. Multi-Platform Detection

Integration of MALDI-TOF MS, ESI-MS, and SEC-MALS enables both rapid high-throughput screening and high-resolution, precise molecular weight analysis under complex conditions.

 

2. Broad Sample Compatibility

Our protein and peptide molecular weight determination service accommodates a wide variety of samples, including recombinant proteins, native proteins, peptide antigens, enzyme digestion products, serum, body fluid samples, and complex protein assemblies. With diverse technologies, we deliver high-precision molecular weight determination across research, clinical, and biopharmaceutical applications.

 

3. Professional Customization and Data Support

Our expert team provides end-to-end services from sample analysis to data interpretation, ensuring scientific rigor and reliability, with comprehensive technical reports supporting both academic and industrial projects.

 

4. Transparent Pricing

Our pricing is clear and transparent, with no hidden fees or additional costs.

 

Sample Submission Suggestions

1. Protein samples: Purity ≥90%, no obvious degradation or aggregation; recommended concentration 0.5–1.0 mg/mL; minimum volume 50 μL per sample.

2. Peptide samples: Purity ≥95%, avoid high salt or interfering buffers; may be submitted as lyophilized powder or solution.

3. Complex samples: For serum, body fluids, or protein complexes, please contact us in advance for dedicated pretreatment guidance.

4. Storage & transport: Samples should be aliquoted into sterile cryovials, avoid repeated freeze-thaw cycles, and shipped on dry ice to ensure stability.

5. Special samples: For samples with special modifications or instability, please provide details in advance; we will offer tailored preparation instructions.

 

MtoZ Biolabs is committed to providing professional and reliable protein and peptide molecular weight determination services for research and industry clients. With state-of-the-art mass spectrometry platforms and SEC-MALS technology, we support diverse sample types and deliver high-precision, reproducible data. Whether your focus is on protein characterization in basic research or quality control in biopharmaceutical development, we provide one-stop solutions to meet your needs. By choosing MtoZ Biolabs, you will benefit from efficient workflows, authoritative data reports, and comprehensive technical support.

 

We warmly invite you to contact us and start your molecular weight analysis project with confidence.