1. assay should be specific for protein of interest 2.
Few assays are able to meet all desired criteria.
For each the criteria listed in A above, describe the consequences if the assay does not meet the criteria 1. Can get false positives 2. Purification will take a long time 3. A significant portion of your desired protein will be used up in the assay and yield will be reduced due to this loss 4. You will be unable to determine yields for each purification step and will be unable to evaluate losses at each step 2.