Question

Investigators wish to purify an enzyme—a serine protease—using affinity chromatography. They attach to the matrix of an affinity column an antibody molecule that binds specifically to a short sequence of amino acids located in the enzyme’s active site. When they apply a mixture of proteins to the column, the protease adheres to the column and the other proteins pass through. To extract their purified enzyme from the column, the investigators add a large excess of the peptide that the antibody recognizes. What should they expect to occur after this treatment?

Answer 1

Answer:

After this treatment, the investigators should expect to get a mixture of the desired enzyme, plus fragments of the peptide used to desorb the enzyme in question.

This would be the result of using a peptide as a desorption solution when the desired protein is a protease,

Assuming that the protease retains its activity in the medium in question, and that the peptide can act as a substrate (which would make sense), as the peptide solution is added, it will interact with and bind to the antibody, but some molecules will also interact with the active site of the enzyme as it desorbs and passes through, culminating on the elution of the hydrolized part of the peptide along with the enzyme.