Deamidation

The trouble with small changes

The trouble with tiny modifications in a complex molecule is the difficulty in trying to find them.

This is certainly the challenge when proteins – particularly those containing the amino acids asparagine or glutamine – have undergone deamidation. It results in the addition or removal of as little as one Dalton of molecular weight to the entire protein structure and it’s very difficult to pick up.

Then there’s the issue of attempting to work out if the modification is really due to deamidation or simply due to variations in isotopic distribution, which is normal and occurs naturally in peptides. Our high-resolution mass spectrometers, coupled with an eye for detail and experienced bioinformatics team, enable us to distinguish between the two causes with reliability and high accuracy.

Furthermore, we can determine the specific sites of deamidation by undertaking peptide mapping using a high-resolution mass spectrometer and mass accuracy such as LC-ESI-MS/MS.

Analyzing deamidation is a key requirement of ICH Q6B.

Technical information

Deamidation is commonly observed as a post-translational modification of the amino acid asparagine, which turns into a mixture of isoasparate and aspartate via a succinimide intermediate. The rate of modification is influenced by factors such as the presence and interaction of surrounding amino acids, pH and temperature buffers. Deamidation of glutamine also occurs, but much less frequently.
You will be interested in finding out whether your protein has undergone deamidation because it leads to a change in isoelectic point (pI) and therefore the presence of charge heterogeneity. We can reliably observe pI by 1D-IEF or IEX-HPLC.

Your contact for Deamidation at Protagen AG

Dr Katja Aschermann Head of Business Development Protein Services. Her team will be happy to assist you with your project. Phone: +49 (0) 231 9742-6300 Email: salesproteinservices@protagen.de