Molecular Weight

We offer accurate molecular weight determination of both proteins and peptides.

Our high resolution instruments can also provide:

  1. Information on protein/peptide modifications: either synthetic or enzymatic.
  2. Estimation of sample purity/confirmation of correct synthesis/expression.
  3. Stability of protein sample, including any degradation/proteolysis that may have occurred.
  4. Information on the micro-heterogeneity present within a sample i.e. the number of modifications and stoichiometry of modifications. In addition, through MS/MS analysis, the location of the modification (refer to Post translational modification analysis) and its amino acid sequence (refer to Protein Identification) can be determined.


Molecular weight picture

Typical mass spectrum of a denatured protein complex containing two
protein subunits(red and blue peaks) and one small molecule (pink).
Molecular weights can be reported to 0.01% accuracy.

For molecular weight determination, we utilise the Orbitrap Elite and the SolariX XR mass spectrometers equipped with a nano-electrospray ionisation.

How to prepare samples for analysis

For molecular mass determination, we require a minimum of 20 µL sample volume at a concentration of 20 µM. Desalting is required prior to mass spectrometry analysis and this service is provided in-house.

Note: PEG, glycerol and detergent are not amenable to mass spectrometry analysis. These must be removed prior to sample submission. Analysis on lower sample volumes/concentrations can be attempted but results are not guaranteed. Please contact us prior to analysis if your sample has stability issues outside its preferred buffer or does not fulfil the above criteria.

Sample Submission

To download the sample submission form click here.

Note: sample submission signifies agreement with our terms and Conditions of Service.