<prompt> Electrophoresis done under pH gradient isIsoosmoticIsoelectricIon exchangeNone  <response>: Ionic buffers called ampholytes and an applied electric field is used to generate a pH gradient within a polyacrylamide matrix. Applied proteins migrate until they reach the region of the matrix where the pH matches their isoelectric point pI, the pH at which a peptide;s net charge is zero. IEF is used in conjunction with SDS- PAGE for two-dimensional electrophoresis, which separates polypeptides based on pI in one dimension and based on Mr in the second Figure 45. Two-dimensional electrophoresis is paicularly well suited for separating the components of complex mixtures of proteins.Ref: Harper;s Illustrated Biochemistry a LANGE medical book twenty-sixth edition Page no: 24 