Application note

Protein Size as an Indication of Structure

The molecular weight of proteins is an important analytical parameter, but it does not provide information on the crucial secondary, tertiary or quaternary structural components which are often vital for their proper function.


By observing the size in solution as well as molecular weight, we can gain insights into the conformation of proteins and their complexes.

Here we observe the relationship between Mw and Rh (as measured by microfluidic diffusional sizing, MDS) in a range of proteins, and note how this relationship can indicate structure.


  • The use of MDS in elucidating the Mw/Rh relationship in proteins where shape is a critical aspect of function provides a rapid yet insightful method for protein scientists.
  • By observing the Rh to Mw relationship, we can elicit structural clues that can highlight clear differences between monomeric globular proteins and those that assume other conformations.


  • Publications and resources

    View all
    • Infographic

      Which protein sizing technique is right for me?

      This infographic lays out the key considerations you should think of when choosing a protein sizing technique.

    • Blog

      Protein DLS result not as expected? Try these troubleshooting tips

      If your DLS result for a protein sample is not what you expected, it could be down to one of these common reasons. Use this list to troubleshoot your DLS protein results fast.

    • Video

      Introducing The Fluidity One - video

      This short video introduces the Fluidity One instrument, how it works, what Microfluidic Diffusional Sizing MDS is, and why native state protein analysis is so vital.

    • Blog

      Protein size - how do I measure it, and why is it important?

      An overview of why protein size matters, and what structural and functional information protein size can reveal. To understand proteins and their function, we have to understand the way they fold, aggregate and interact. Conformation is key to protein function and can be revealed by measuring size. Different methods for measuring protein size are summarised, and comparison is made, considering the method, range, cost and limitations of each technology.

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