ANTI-ENZYME IMMUNITY 275 



rupted by the drying process, and the inhibitor is ehminated by the 

 low-temperature ethanol fractionation. 



a. Comments on the Possible Nature of the Role of Bacterial 

 Fibrinolytic Factor. The above cited important studies by various in- 

 vestigators no doubt have very much broadened our knowledge of the 

 process of fibrinolysis. There appear, however, certain questions which 

 need to be investigated to further our understanding of this process. 

 One would like to know the chemical nature and the properties of the 

 substance which apparently is present in serum and keeps the serum 

 protease in an inactive state. This substance is apparently readily 

 eliminated by treatment with organic solvents such as chloroform. Is 

 this a lipid-like substance comparable to thromboplastin or one of its 

 degradation products of non-protein nature, or a polypeptide com- 

 parable to the trypsin inhibitor obtained from pancreas? The inhibition 

 of activated serum protease by pancreatic trypsin inhibitor does not 

 necessarily mean that the inhibitor component of the inactive serum 

 protease complex is chemically identical with the pancreatic trypsin 

 inhibitor. The inability of the bacterial factor to influence the inhibi- 

 tion of serum protease resulting from combination with pancreatic tryp- 

 sin inhibitor may indicate that the inhibitor component of the in- 

 active state of serum protease is different from the trypsin inhibitor. 

 The activation of serum lytic factor by organic fat solvents suggests 

 the possibility that this inhibitor serum component is a lipid-like 

 substance. Does the material recovered from organic solvents exercise 

 inhibition when returned to the activated serum protease? If it in- 

 hibits, is this inhibition antagonized, or destroyed by streptococcal 

 factor? 



The possibility that a lipid-like substance is removed by solvents, 

 etc., is strengthened by an observation (Tagnon, 1942) that chloroform- 

 activated serum loses its fibrinolytic power when treated with throm- 

 boplastin. Tagnon reported that oxalated plasma contains antilvtic 

 substances. He demonstrated that thromboplastin exercises a powerful 

 antilytic effect. A reaction system containing chlorofonn activated 

 serum enzyme was capable of digesting fibrinogen, without producing 

 fibrin clot formation. In the presence of a small amount of thrombo- 

 plastin the same system caused the clotting of fibrinogen but no lysis 

 of fibrin clot took place. That this inhibition may be considered as 

 the result of a direct action of thromboplastin on the fibrinolytic 



