Sodium sulfate, starch fractionation

The commercial production of starch fractions, based on the principle of fractional precipitation treated in Section IV, started in Holland around 1955. In the process employed, potato starch is dissolved under pressure, at an elevated temperature, in an aqueous solution of magnesium, ammonium, or sodium sulfate, or a mixture of two or of all three of them. For simplicity, attention will here be restricted to magnesium sulfate. 

Albumin and globulins can be analyzed by the same procedure as for total proteins after fractionation by salting out with either sodium sulfate or sodium sulfite. More detailed information may be required about the protein fractions (a, j8, 7 globulins), in which case starch gel electrophoresis can be used to separate the proteins. Micro-Kjeldahl analysis of proteins is used when highly accurate data are required the biuret method is accurate to about 4%. 

Fig. 4. — Monitoring of the Multiple Molecular Forms of Tomato Pectinesterase by Starch-gel Electrophoresis.98 [ENZ, detection of pectinesterase activity by paper print with pectin and Bromothymol Blue PROT, protein staining with nigrosin O, origin. Key A, 1 crude tomato extract after ammonium sulfate salting-out, and dialysis 2 pectinesterase fraction from column of DEAE-Sephadex A-50 3 and 4 pectinesterase fractions from column of Sephadex G-75. B, Two parts of the same gel after horizontal slicing 1, 500 fig of the isolated form of pectinesterase from a column of CM-Seph-adex C-50 with 175 mM phosphate-sodium chloride buffer 2, active fraction at 150 mM buffer 4 and 5, 250 fig and 1 mg of the isolated form of pectinesterase, respectively.]...

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