Dear Zheila.

Making a brief consult about von Willebrand factor I could see that it is present in several multimer sizes from about 500 kDa to up to 20000 kDa. Considering this, you could use Thermo's NativeMark™ Unstained Protein Standard as it ranges from 20 kDa to up to 1200 kDa. It would not be ideal for western blotting, as it is unstained, however it seems to be compatible with visualization techniques as Ponceau staining so you could use that to see if, for example, transferences were complete.

I would like to ask you if there is any particular reason for you to use agarose gels for your electrophoresis (as this is not the most common approach). Is it because you're interested in the highest molecular range multimers? Is that is the case I'm sorry to tell you that I've not heard of any protein standards of such a high range (>2000 kDa). However, in this paper (https://www.ncbi.nlm.nih.gov/pubmed/22585481) the authors use reference proteins such as human soleus titin (1 band at 3700 kDa) or human ventricle titin (2 bands at 3300 and 3000 kDa) as molecular weigh "markers" maybe you could use that approach. I've attached the figure of that experiment so you can see it.

I hope that this helps, I wish you the best with your experiments.

Regards, 

Andrés

P.S. Here is the citation of the paper in which the figure is:

Greaser, Marion L., and Chad M. Warren. "Protein electrophoresis in agarose gels for separating high molecular weight proteins." Protein Electrophoresis: Methods and Protocols (2012): 111-118.

Andrés,

Thank you for your help. I will look at these options before I go further. Also, thank you for the link to the paper.

Best regards,

Zheila A.

Anything that has IgM (about 1 M) could help.