[Yeast] (no subject)

[jkellosa from mappi.helsinki.fi]

Dear all,

A lab technician who I work with got both pure protein and wanted protein 
with two contaminating bands, both of which molecular weight is higher than 
the molecular weight of the wanted protein, from different batches of 
protein purification. The molecular weights of the contaminating bands are 
not high enough to account for different oligomerization states of the 
wanted protein.

The two contaminating protein bands hang on really tightly with the wanted 
protein and we have not been able to get rid of them.

I dont know what is the difference between purifications which produce pure 
protein and the purifications which don't, but I suspect that at least 
there has been differences at how long the cells have been growing since 
they were harvested.

This leads me to my question that I want to ask from you:

Have you ever had problems with contaminating proteins (stable 
proteins/chaperons hanging along, modifications of the wanted protein ?) 
when S.cerevisae cells have been in a certain growth phase ?

-Juho Kellosalo