[Preparation of a prekallikrein concentrate and determination of its activator in blood derivatives].

The determination of an increased level of a fragment of the Hageman's factor (HFf) in preparations prepared from blood plasma can be an index of their potential reactivity in clinical application. The demonstration of the presence of HFf is based on the fact that the preparation containing this factor is able to activate the prekallikrein substrate. When the concentration of prekallikrein is sufficient, the amount of the developed active enzyme kallikrein is proportional to the amount of HFf. The amount of kallikrein is determined by cleaving the specific chromogenic substrate NO-Pro-Phe-Arg-pNA. The presence of salts negatively influences the rate of the activating stage of the reaction. The described preparation of the prekallikrein concentrate from the human blood plasma is a modification of the method of Levy and Sober) for the separation of the human immunoglobulin fraction. The blood plasma with an addition of hexadimethrinebromide is sorbed on DEAE Sephadex equilibrated with 0.0175 mol/l phosphate buffer pH 6.3 with hexadimethrinebromide in a vessel with an intact surface. Prekallikrein together with IgG are not sorbed on the anion exchanger under the above-mentioned conditions. The obtained supernatant can be employed as the prekallikrein substrate to determine the HFf activity in blood derivatives.