You are trying to purify a protein that is soluble in a solution of 2 M ammonium sulfate. After centrifugation to remove other proteins that have precipitated at this high salt concentration, you recover the supernatant to assay the target protein's activity in a cell culture system.
(a) Explain why the cells die when incubated with the supernatant.
(b) What procedure could you perform to correct the problem? (Hint: See Section 2-1D).