ABSTRACT
The classical method for carrying out this separation of water-soluble serum proteins (albumin) from insoluble proteins (globulin) generally involved a ten-to-twenty-fold dilution of the serum with water, accompanied by the addition of acetic acid. None of the distinctions and refinements in salt precipitation techniques ever led to any clear-cut separations of protein fractions with sharply differing properties. In 1921 Howe replaced ammonium sulfate with sodium sulfate which does not interfere with Kjeldahl analysis of protein nitrogen. Precipitation with ammonium sulfate at room temperature became the classical method of protein fractionation. Otto Porges and K. Spiro divided serum globulin into one euglobulin and two pseudoglobulin fractions at progressively greater concentrations of ammonium sulfate. The biuret color must be standardized with protein of known concentration. In 1937 Arne Wilhelm Kaurin Tiselius reported his development of a new electrophoresis instrument that overcame the difficulties of previous designs and permitted the measurement of the electric mobility of proteins in a mixture in solution.
