DelsaMax CORE in Molecular Weight Analysis


Molecular weight - BSAI’d like to direct you to another source of useful information on applications of dynamic light scattering. If you go to the web page you will find a button inviting you to ask for application downloads. Click on that, then fill in your details, and you will be offered a very interesting selection of application studies.

I’ve just been looking at one that involves use of the DelsaMax CORE, part of the DelsaMax range of dynamic light scattering instruments from Beckman Coulter, in molecular weight analysis. If you want the full detail, do download the notes yourself. In the meantime, I’ll give just a brief overview.

Determining precise molecular weights of proteins and antibodies is very important to molecular biologists. Through analytical determination of molecular weights it is possible to study such processes as antibody self-association interaction, antibody-antigen interaction and protein stability. To date, measurement has tended to use gel electrophoresis, but this is far from ideal. For a start, it does not measure directly but needs calibration standards for each test. To measure the molecular weights of antibodies and proteins directly, you can use analytical ultracentrifugation, mass spectrometry and various other techniques.

However, if you want to determine the molecular weights of proteins directly and rapidly, a combination of dynamic light scattering (DLS) and static light scattering (SLS) is the best approach. One reason why this has become increasingly popular is the fact that it works with volumes as small as 1 µl and gives you a precise molecular weight in a matter of seconds – without destroying the sample. Used together as ensemble methods, SLS and DLS are statistically significant. Of even greater importance is that they are able to deliver measurements of protein in a buffer, without dilution, and without loss of the precious sample. This is particularly valuable in the case of monoclonal antibodies.

The downloadable study describes how well DelsaMax CORE performs in analysis of protein and antibody samples at low concentrations. Light scattering by mouse monoclonal antibodies, at a concentration of 0.5 mg per ml, was only slightly greater than that produced by the background buffer solvent. Using the DelsaMax software, results were available in less than 20 seconds. With increased – although still quite low – concentrations of bovine serum albumin (BSA), it was possible to measure molecular weights to an impressive standard of accuracy, over a wide temperature range, while tracking the protein’s aggregation at temperature levels in excess of 70 deg C.