INHIBITION OF BOVINE LEUKOCYTE THIOLTRANSFERASE BY ANTIINFLAMMATORY DRUGS AND ANTI-HISTAMINIC DRUGS

Thioltransferase was partially purified from bovine leukocyte using sonication, heat treatment at pH 5.1, Sephadex G-50 gel filtration and isoelectric focusing techniques. Isoelectric point (pI) of 8.3 for leukocyte thioltransferase was quite different from pI of 6.5 for erythrocyte enzyme. Bovine leukocyte thioltransferase was employed in a study on the influence of 12 anti-inflammatory drugs and 7 anti-histaminic drugs. Piroxicam which is a well-known anti-inflammatory drug demonstrated the most powerful inhibitory effect on enzyme activity. Inhibition of piroxicam was noncompetitive, and the K(i) value measured 55.0 muM in the experiment involving bovine leukocyte enzyme. Tranilast which is a typical anti-histaminic drug most strongly inhibited the enzyme activity and the K(i) value of the medicine was 20.3 muM (noncompetitive). Bovine liver and erythrocyte thioltransferases also were effectively inhibited by both medicines similar to leukocyte enzyme.