[Effect of modifications of the protein moiety of thromboplastin (factor III) on its activity]

The role of protein moiety of tissue thromboplastin under its specific enzymatic modification and the effects of some protease inhibitors were studied. Treatment with HCl, pepsin and papain was followed by a decrease in the biological activity of thromboplastin, which was unaffected by the inhibitors of some proteolytic enzymes (DFP, monoiodoacetate and o-phenanthroline). It was assumed that the protein component of thromboplastin fulfils a structural function in the assembly of the lipoprotein matrix, on which surface the enzymatic reactions of blood coagulation are known to occur.