Optimized Sequencing using Multi-Enzymatic-Limited-Digestion (MELD)

As primary sequence plays an essential role in structural characterization of proteins, it is important to have tools allowing providing a complete or very high sequence coverage. Generally, this cannot be achieved by traditional trypsin digestion because large parts of proteins are not detected or efficiently sequenced.

We propose here a strategy to overcome this limitation and provide you with very high sequence coverage.

The protein is digested in solution by an enzymatic cocktail after reduction and alkylation. The resulting peptides are analyzed by LC-MS/MS.

Once data recorded, they are submitted to database search in order to identify proteins. Amino acid sequences from the original organism have therefore to be available in public databases like SwissProt, NCBI, etc. or should be provided.

Alternatively, if the sequence is unknown, de novo partial sequencing can be achieved using PEAKS 7 software. The software builds ladder of amino acids based on the MS/MS fragments of the peptide and the accurate mass of the peptide. Those tags can be submitted to database search to see if homology is found with existing proteins.

The price includes the enzymatic digestion, the LC-MS/MS analysis, the database search and the reporting. Please contact us if de novo sequencing has to be performed. Contact us for a personalized quote.

What is delivered?

A list of proteins identified with relevant statistical values. For the protein(s) of interest, a list of all identified peptides and peptide modifications will be provided.

Report and results will be sent by email. Results are usually available in 15 working days.

Raw data are available on request.

What is needed for these analyses?

At least 50 µg of a purified protein are required. Please note that if the buffer is not compatible with the workflow, an additional purification step (see Sample Preparation Section for more details) will be performed. If you have less material, please contact us to discuss the feasibility of your demand.

Analysis Request Form for MELD of Pure Protein by LC-ESI-MS/MS