Introduction
Top-down is a analysis method that sequencing or characterizing intact proteins without any truncation, which the
method allows analysis of intact proteins without the need to digest peptides.
Top-down mass spectrometry has unique advantages in identifying protein forms with multiple post-translational
modifications and/or unknown alterations. The process that intact proteins are introduced into the mass spectrometer
for analysis reduces the complexity of the initial sample and crucially preserves information about combinatorial
PTMs, sequence variants, alternative splicing and so on. Thus, this strategy can preserve labile modification motifs
that are largely lost when using shotgun and CID for fragmentation in protein therapeutic assays, such as monoclonal
antibodies and recombinant proteins.
Fig. 1. Top-down for
protein PTM characterization. (Zhang H, et al., 2011)
Our Services
With advanced mass spectrometry platforms and rich experience in proteomics analysis, Creative
Proteomics provides you with top-down mass spectrometry analysis services for protein
post-translational modification to help your research projects.
At Creative Proteomics, our scientists and technicians with experienced proteomics take a top-down
approach to decode your protein, while preserving full PTMs information. Throughout the service cycle, intact
proteins are ionized by electrospray ionization (ESI) or laser matrix desorption ionization (MALDI). The resulting
ions are fragmented by collision-induced dissociation (CID), electron capture dissociation (ECD), or electron
transfer dissociation (ETD) and analyzed in a tandem mass spectrometer to obtain protein information.
Notably, top-down proteomics stills under development and confronts with technical challenges in sample preparation,
but the unique advantages mentioned above still make it a promising tech solution for characterization of
post-translational modifications. It is complementary to bottom-up analysis and enables large-scale analysis of
protein post-translational modifications, thus providing comprehensive and high-quality services for your PTMs
analysis.
With cutting-edge equipment and expertise in protein sequencing and mass spectrometry, we provide one-stop top-down
based PTMs characterization services. You only need to tell us the purpose of your experiment and send your samples
to us, we will take care of all the follow-up matters of the project.
Experiment Process
Advantages of Top-Down Mass Spectrometry
- The time-consuming protein digestion required for bottom-up methods is eliminated.
- Complete protein sequences and the ability to locate and characterize PTMs are achived, and most of the unstable
structural features that are disrupted in bottom-up MS is preserved.
- Information for rapid characterization of mature N/C termini and other PTMs.
- PTM combinations on large segments can be detected and positional isomers with the same molecular weight can be
distinguished.
Sample Requirements
- Tissue samples: Plant tissue samples > 200 mg, blood samples > 1 mL (with EDTA for anticoagulation of
plasma), serum > 0.5mL, urine> 2 mL, animal tissue samples >1 g, cell samples > 5X107
cells, microorganisms> 200 mg (dry weigh).
- Protein samples > 1 mg.
Thanks to our powerful mass spectrometry sequencing platform, Creative Proteomics provides top-down
based PTMs characterization services for global researchers. Please feel free to contact us with any questions regarding protein post-translational modification analysis.
References
- Zhang H, Ge Y. (2011) Comprehensive analysis of protein modifications by top-down mass spectrometry. Circ
Cardiovasc Genet. 4(6):711.
- Siuti N, Kelleher N L. (2007) Decoding protein modifications using top-down mass spectrometry. Nat
Methods. 4(10):817-821.
