Characterization of the bacterial enzyme “Thromboplastinase”

Abstract

1. 1. The action of the enzyme “thromboplastinase” has been compared with that of a Clostridium perfringens culture filtrate and purified α-toxin, and of a Bacillus cereus phospholipase. 2. 2. All enzymes released acid-soluble phosphorus from purified lecithin. In the conentrations used, the clostridial enzymes were most active. In addition, all enzymes liberated acid-soluble phosphorus from human brain thromboplastin and reduced the clot-accelerating activity of thromboplastin. In these cases, however, thromboplastinase was most active. 3. 3. The acid-soluble compounds released by thromboplastinase, by the B. cereus phospholipase, and by C. perfringens lecithinase were identified as phosphocholine, phosphoethanolamine,sb and phosphoserine and were measured quantitatively. Thromboplastinase liberated phosphocholine most actively, and the other compounds approximately equally. The clostridial enzymes liberated as much phosphocholine as did thromboplastinase, but less phosphoethanolamine, and little or no phosphoserine. The B. cereus phospholipase released small amounts of all three compounds. 4. 4. The destruction of thromboplastic activity does not appear primarily due to the lecithinase activity of thromboplastinase, but rather to the breakdown of phosphatidylethanolamine and possibly phosphatidylserine by this enzyme. The relation between thromboplastinase action and that of the other enzymes studied, especially that of the B. cereus phospholipase, is discussed.