S. cerevisiae protein secretion levels (mass) in minimal media - (Feb/07/2019 )
I am trying to reproduce an assay from a publication (doi:10.1016/j.febslet.2010.11.026) in which a Ddi1 (VSM1) mutant of S. cerevisiae is reported to secrete significantly higher levels of protein into the media than its wild-type parent.
The assay uses overnight growth in SM (final A600nm~2) followed by protein concentration determination in the supernatant by the RC DC (Bio-Rad) kit (which is a Lowry assay). In the publication the data is only given as a fold-change mutant v wild-type rather than total mass as assayed.
Using a similar set-up I am unable to detect any protein in the supernatant (using the Pierce Coomassie-based protein assay). Workable range for the two assay should be equivalent.
I'm wondering whether anyone as any information regarding the mass of protein expected to be secreted under these conditions so I can sanity check it against what I'm able to detect with my protein assay.
the compatibility of various additives are different for the lowry and coomassie assays, as are the linearities. are you sure that your medium is not interfering with the protein assay?