Prekallikrein in human citrated plasma was activated by incubation with acetone, 17 or 25% (v/v). EDTA‐2Na was added before or after the evaporation of acetone. Determinations of the relative activities of the enzyme preparations were based on the release of kinin from the 3 functional states of kininogen in human citrated EDTA‐plasma as described by BRISEID et al. (1973). Incubations were carried out at 37° or at 0°. The kininogen 1/kininogen 2 activityratios were the same at 37° and 0°, indicating that the kininogenase activities tested were the same. The relative activities of the different kallikrein preparations varied with the type of kininogen used, possibly reflecting the presence of more than one kininogenase. Purification of the kallikrein combined with determinations of kininogen 1/kininogen 2 activity‐ratios must be carried out to solve the problem.
Prekininogenases in rat citrated plasma were activated with acetone (20% v/v). EDTA was added after the evaporation of acetone to increase the activity of the enzyme preparation. The preparation was tested for kininogenolytic activity (release of kinin in 60$dG‐heated human citrated EDTA‐plasma), esterolytic activity (hydrolysis of benzoyl arginine ethyl ester or tosyl arginine ethyl ester) and caseinolytic activity. The decrease in urokinase activable caseinolytic activity together with the development of spontaneous caseinolytic activity which could be inhibited by lima bean trypsin inhibitor, and also experiments on the hydrolysis of lysine ethyl ester, suggested the presence of plasmin in the enzyme preparation. When enzyme preparations were prepared from plasma of rats pretreated with carrageenin, ellagic acid or serotonin, significant reductions in the above mentioned activities were observed. A good correlation was obtained between the two acyl‐arginine esterase assays, while no such correlation was obtained between the kininogenase and the esterase assays. This fact probably reflects differences in the relative amounts of kallikrein and plasmin present.
Estimates of prekallikrein levels in plasma specimens from patients with migraine and from healthy individuals were obtained by determining the benzoyl-arginine ethyl ester (BAEe) esterase activities developed on activation with kaolin, as suggested by Costerase level- 'n the patients and in the control material, and kinetic data provided no evidence of a difference in inhibitor levels. Only very low BAEe esterase activity was registered in samples of cerebrospinal fluid obtained from the patients and no significant difference between attacks and free intervals was detected. When citrated EDTA-treated plasma was activated with acetone-incubated normal plasma containing prekallikrein activator (factor XIIf), no significant difference in BAEe esterase activity was noticed between plasma from the patients and that from the control persons. When, however, citrated plasma without EDTA was used, a significantly higher peak level of esterase activity was registered in the patient plasma. This observation might suggest the presence of a factor positioned between active factor XII and prekallikrein, and present in higher amounts in plasma from patients with migraine than in healthy individuals.
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