Protein Structure Characterisation and Conformation

Protein structure and conformation characterisation in line with EMA, FDA and ICH guidelines includes sequencing, peptide and disulphide bridge mapping and PTMs

Protein structure characterisation is fundamental to biologic development and ongoing quality control of products, in terms of identification and product homology.

Proteins have complex structures which must be well understood from the primary sequence of amino acids through to higher order structure. In accordance with the ICH Q6B Guidelines, it is important to perform an overall assessment of structural heterogeneity to demonstrate protein identity and consistency of manufactured batches. The tests selected can be qualitative in nature, but should be highly specific for the drug product and should be based on unique aspects of the molecular structure. 

Our protein scientists have a great deal of expertise in delivering analytical programs that are strategically designed to optimise the data required to determine or confirm identity, explore patterns of heterogeneity and demonstrate consistency in quality of the drug substance. 

We provide extensive protein characterization during the development phase and, where necessary, following significant process changes.  To support your submission, we can provide data to Good Laboratory Practice (GLP) or Good Manufacturing Practice (GMP), as appropriate, with comparison against the most suitable reference standard, if available. 

Our wide breadth of technology combined with the unique level of expertise and experience makes Intertek the perfect partner to expedite your protein structural characterisation programs to meet your development, submission or ongoing processing needs. 


We apply a number of approaches to initially quantitate the distribution of amino acids. This is then accompanied by sequencing or peptide mapping or sequencing studies using a broad range of enzymatic or chemical digestion followed by LC-MSMS analysis.

Intertek conduct selective fragmentation of protein into discrete peptides by enzyme or chemical digestion followed by high-performance liquid chromatography and electrospray mass spectrometry analysis and /or MALDI-TOF MS.  Once the methodology is established we take the methods through validation and application in batch release or stability assessments.
Confirmation of the amino- and carboxy-terminal amino acids is performed by LC-MSMS specifically with the aims of product identification and to establish homogeneity, where understanding the type and extent of modifications at either termini, is a fundamental aspect of product quality control.
Where cysteine residues are present in the molecule e our scientists perform a qualitative/semi-quantitative assessment of the position and extent of expected and mismatched disulphide bridges by extended LC-MSMS peptide mapping studies, MALDI-TOF or Electrospray MS and colorimetric tests for free sulfhydryl groups.
Our post translational modification analysis experts apply a strategic approach to PTM analysis during early development phases to help you to establish product acceptance criteria and as part of structural characterization studies and comparability programs, stability studies or quality control testing.
Our biologics characterisation group provides higher-order structure analysis via a suite of orthogonal techniques including circular dichroism (CD), nuclear magnetic resonance spectroscopy (NMR) and infrared (FTIR) or fluorescence spectroscopy.
Glycosylation studies are designed product specific, however, these typically include determination of the levels of neutral and amino monosaccharides as well as sialic acids, assessment of glycoform distribution and  glycan structure elucidation.  Multiple technologies are applied in these determination including selective enzymatic cleavage and MALDI-TOF Mass spectrometry HPLC, HILIC, IEX or CE-LIF, to provide the level of structural information required.
For antibody drug conjugates (ADCs) our scientists determine the  position of attachment of the toxin to the linker and subsequently protein, also known as the sites of conjugation. This is typically achieved using LC-MS and LC-MS/MS following enzymatic digestion.  The same logic methods can also be applied to establishing the position of PEGylation and other conjugated forms.
Need help or have a question? +1 800 967 5352

Need help or have a question?

+1 800 967 5352
+44 161 721 5247
+41 61 686 4800