To determine the isoelectric point of a protein, first establish that a gel: a) contains a denaturing detergent that can distribute uniform negative charges over the protein surface. b) exhibits a stable ph gradient when ampholytes become distributed in an electric field. c) is washed with an antibody specific to the protein of interest. d) neutralizes all ionic groups on a protein by titrating them with strong bases. e) relates the unknown protein to a series of protein markers with known molecular weights.