Practice question

In isoelectric focusing, a stable pH gradient is established using carrier ampholytes or immobilized buffers spanning acidic to basic range. Proteins introduced into gradient acquire positive charge below their pI and negative charge above, causing migration in electric field. As movement proceeds, net charge diminishes upon approaching pH equal to isoelectric point, where protein becomes electrically neutral. Loss of electrophoretic driving force halts further migration, while diffusion is counteracted by focusing effect, concentrating proteins into sharp zones at characteristic positions. Focusing does not terminate arbitrarily at electrode positions but at specific pH matching individual pI properties.