In a Biochemistry Laboratory a Student Added Ammonium Sulfate to a Tube

Multiple Choice

In a biochemistry laboratory a student added ammonium sulfate to a tube containing a buffered protein solution.The student then centrifuged the solution.What was the student probably trying to do?

A) Change the pH of the buffer solution to solubilize all proteins.
B) Hydrolyze the proteins into their constituent amino acids to determine the percent composition.
C) Derivatize the N-terminal amino acid of all proteins.
D) Selectively precipitate and purify a certain protein.