Über den Einfluss der Polyphosphate auf die Löslichkeit einiger Plasmaproteine und die Möglichkeit der Plasma‐Fraktionierung mit Polyphosphat

The influence of polyphosphate on the solubility of the more important human plasma proteins, namely albumin, y‐globulin, fibrinogen and metal binding β 1 ‐globulin, is studied. Besides the polyphosphate concentration the two main factors which determine the solubilities are the ionic strength and the pH, especially the latter. The influence of the temperature is relatively small between 0 and 20°C. On lowering of the pH the solubility of the proteins drops within a narrow pH‐range (0,5–1 unit) to practically zero. The precipitating activity of the linear polyphosphates is independent of the polymerisation degree if equivalent amounts are added. With the lowest oligophosphates however remarkable differences in their action were found. The pH necessary for the precipitation of the proteins in the presence of polyphosphate differs sufficiently from one protein to the other to render a fractionation of their mixture possible. Plasma may thus be divided into several fractions by lowering stepwise the pH after addition of a sufficient amount of polyphosphate.