Bovine Prekallikrein Activator with Functional Activity as Hageman Factor

Abstract

A substance which activated prekallikrein on addition of ellagic acid was isolated from the euglobulin fraction of bovine plasma by chromatographies on CM-Sephadex C-50, DEAE-Sephadex A-50 and once more on CM-Sephadex C-50. This prekallikrein activator existed in plasma in an inactive precursor form and tended to change progressively into an active form during the purification procedure. The final preparation showed about 70% of the full prekallikrein activating activity induced by the addition of ellagic acid. About 1 mg of a purified preparation was obtained from 15 liters of bovine plasma. The apparent molecular weight of the activator and its precursor protein was calculated to be 95,000 by gel filtration and about 89,000 by sucrose density gradient ultracentrifugation. The prekallikrein activator had functional activity as Hageman factor and corrected the coagulation defect of Hageman factor-deficient human plasma. Its clot promoting activity was found to be parallel with its prekallikrein activating activity on polyacrylamide gel disc electrophoresis. The prekallikrein activator was similar to the bovine Hageman factor purified by Schoenmakers et al. with respect to its molecular weight, chromatographic behaviours, inhibition by trypsin inhibitor of lima bean, and abilities to activate prekallikrein and to hydrolyze arginine esters.