A full characterization of your recombinant protein requires confirmation of both the expected N- and the C-terminal end of the protein.

This is not an easy task as many proteins may be modified in the terminals! Some proteins are N-terminally modified by acetylation, pyroglutamic acid and other blocking groups that will prevent standard N-terminal sequencing by Edman degradation to be successful. Some proteins contain signal sequences that may not be correctly process, and many proteins are truncated as part of the degradation process. Traditionally, C-terminal sequencing has had a very low success rate. 

Alphalyse offers both N-terminal Edman sequencing, as well as a new service based on In-Source-Decay (ISD) MALDI mass spectrometry.

N- and C-terminal sequencing of purified proteins using In-source-decay (ISD) MALDI mass spectrometry is offered as part of Alphalyse’s protein analytical services which are designed to assist pharma, biotech, academic and CMO customers in the purification and development of natural and recombinant protein products.

The analysis typically provides sequence confirmation of 20-50 residues from both the N-terminal and the C-terminal of the intact protein in a single ISD MALDI mass spectrum. This sequencing technique has several advantages over traditional N-terminal Edman sequencing:

• The sequencing covers both protein termini and provides both the C-terminal and N-terminal sequence.
• N-terminal blocked proteins can be sequenced.
• The sequence reads are long providing 20-50 residues from both termini in just one single ISD MALDI spectrum.

Our application note "N- and C-terminal sequencing by MALDI ISD #200902", demonstrates that the technique can be applied to a variety of natural and recombinant proteins and monoclonal antibodies.

To be able to provide this service we will need purified protein (>80% purity), in-solution or as a  lyophilized sample in microgram quantities.

Please contact us to discuss your specific project in more detail.  We will provide you with a full project proposal within 2 days that includes analysis protocols, timelines and costs.