Answer: Option D.
Proteins can be purified at the isoelectric points.
Explanation:
Protein purification is a technique of separating or extracting one of more protein molecules from a complex mixture for individual analysis.
Proteins are purified according to the protein isoelectric points.
Isoelectric points or Pl is pH at which the net charge of protein is zero. Protein is purified according to its isoelectric point by making the protein to pass through ion exchange column or a pH graded gel.
