I use an affinity column to purify a protein, "X" from cell lysate. The specific activity of the protein is very low after this step. So I run the affinity-purified sample through an anion exchanger, and collect the early fraction. This eluate has very high specific activity. My results from a PAGE and Western blot after each step are shown. Also shown are the enzyme kinetics after the affinity purification, and after the anion exchange column. Based on all these data, what is your BEST explanation?