5. You have a cell lysate that contains a mixture of proteins listed in the table below. In order to purify the protein D from the lysate you employ a two-step procedure. a Step1: You decide to use cation exchange chromatography.You prepare a buffer solution For the cation exchange column. What is the pH of the buffer solution? In order to elute those proteins that are immobilized on the column, you then apply a Linear salt gradient, with NaCl concentration gradually increasing from 0 to 1M. Indicate The order in which the proteins bound to the column will elute as the salt concentration increases. Step2: Next, you use size-exclusion chromatography. Which proteins from part (a) will you load on to the column? In what order will the proteins elute from the column (starting with the one that elutes first? 4. Were you able to successfully purify protein D? Q Once you purify D, you analyze it by SDS-PAGE. In the SDS-PAGE experiment, you Visualize a single band at 30kDa in the absence of -mercaptoethanol. However, in the Presence of -Mercaptoethanol the SDS-PAGE shows two bands, corresponding to molecular Weights of 30kDa and 15kDa. What can you conclude about the native quaternary Structure of the protein D.(You may use a picture to help with your description.)