Hello, I recently performed a BCA and Bradford assay to determine my total protein content following a membrane purification. The two kits gave me approximately 0.89 and 1.1 mg/ml total protein (was just seeing if the two kits gave approximately same value). I then compared my recombinant protein to a GFP standard and got 206ng of my recombinant protein in total. These all came from the same 300ml total cell culture volume, which after completing the membrane prep were resuspended in 2ml total volume. So my question is how do I convert my 206ng into mg/L?
It will help knowing in which volume you have those 206 ng. Then, it will be easy to convert the units to mg/L.
Hope it helps!
David
You got 0.89 mg/ml from BCA and 1.1 mg/ml from Bradford, presumably based on comparison to a protein standard curve (usually bovine serum albumin). The total volume of the sample was 2 ml, so the total amount of protein was 2 x 0.89 = 1.78 mg y BCA or 2 x 1.1 = 2.2 mg by Bradford. Let's call it 2 mg, the average of the two measurements. This came from a culture volume of 0.3 L, so the yield was 6.7 mg/L. This is total membrane protein, apparently.
I don't understand the part about comparing your recombinant protein to a GFP standard and getting 206 ng. How was this done? In any case, if you determined that your prep contained 206 ng of the recombinant protein of interest (out of 2 mg of total protein), then the yield was 206 ng/0.3 L = 687 ng/L.There is no point in converting it to mg/L.
The purity is 0.000206 mg/2 mg x 100% = 0.01%.
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