ISOLATION AND CHARACTERIZATION OF RAT PLASMA GLANDULAR KALLIKREIN
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Date
1985
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Abstract
A method was developed to purify glandular kallikrein present in rat plasma by using Sepharose-Aprotinin affinity chromatography and elution of the enzyme with p-aminobenzamidine. The isolated enzyme liberated kinins for kininogen II of low MW (sp. act. 14 ng kinins/min .times. mg) and p-nitroaniline (pNA) from the substrate S-2266 (sp. act. 1.23 nmol pNA/min .times. mg); it was inhibited by aprotinin, benzamidine and rat urinary antikallikrein antibody but not by ovomucoid. In polyacrylamide gel electrophoresis, the enzymatic activities of the preparation were associated with 2 light protein bands of MW equal to that of urinary kallikrein (35,000 daltons). Using this method, the recovery of [125I]kallikrein added to the plasma was 82-88%. The concentration of the enzyme in normal rat plasma was equivalent to 6.1 .+-. 2.1 ng kallikrein/ml. The mean value found in nephrectomized rats was 20.0 .+-. 6.3 ng kallikrein/ml. This increment was highly significant (P < 0.001). These results confirm the presence of glandular kallikrein in plasma which had been detected by other methods; they also demonstrate that the material purified from plasma is enzymatically active, suggesting that kallikrein may play a biological role in the control of blood circulation.