A mixture of four proteins of pls 11, 7, 5 and 3 are loaded on DEAE anion-exchange column equilibrated with low ionic strength buffer of pH 8. Which of the four proteins would be expected to be retained on the column?

DEAE is a positively charged anion-exchange column, meaning it binds negatively charged proteins. At pH 8, proteins with a pI lower than the buffer pH of 8 will carry a net negative charge and thus be retained on the column. The proteins with pI 7, 5, and 3 all have pIs less than 8, so they are negatively charged at pH 8 and will be retained, whereas the protein with pI 11 will be positively charged and flow through.