Design an experiment to purify protein x on an cation-exchange column. protein x is contained in a protein homogenate at ph 7. protein x has an isoelectric point of 7.5. indicate which of the items on the right are necessary and in which order to apply them to the sample. clear all first technique to apply: second technique to apply: third technique to apply: fourth technique to apply: collect the fraction containing protein x that comes out during the previous step. decrease the ph of the protein solution to 6.0. increase the ph of the protein solution to 9.0. pour the protein homogenate at its proper ph through the column. pour a salt gradient from high salt concentration to low salt concentration through the column. pour a salt gradient from low salt concentration to high salt concentration through the column.