I've got a protein that I need to reconstitute at 100ug/ml in PBS containing at least 0.1% of BSA, however in the CoA it says that it is supplemented with 50ug BSA per 1ug as a carrier. Do I need to add more, buy preparing PBS with 0.1% BSA, or is it enough, since it already have BSA in the formulation? I don't know if it helps, but it says the same thing in the CoA of the carrier free version of the protein.
0.1% BSA is 1 mg/mL.
The protein is supplied with 5 µg per µg of protein.
If you reconstitute the protein at 0.1 mg/mL, the BSA concentration will be 0.5 mg/ml, so you will have to double the BSA concentration to reach 1 mg/mL.
I suggest you prepare a solution of 10 mg/mL BSA in PBS. Then you can add a small volume to increase the BSA concentration without diluting the other protein very much.
Suppose you have 1 mL of protein at 0.5 mg/mL BSA.
1 mL x 0.5 mg/mL + X mL x 10 mg/mL = (1+x) mL x 1 mg/mL
X=0.056 mL
You would add 56 µL of 10 mg/mL BSA to your 1 mL solution. The other protein would be ~95 µg/mL after dilution, with 1 mg/mL BSA.
If you don't want that much dilution, make a higher concentration BSA stock solution.
Or, dissolve your protein at 0.2 mg/mL, such that the BSA concentration will be 1 mg/mL. Then dilute with 1 mg/mL BSA to the desired concentration.
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