ANTI-ENZYME IMMUNITY 265 



fibrin, or whether the digestion of the intact portions of the fibrin- 

 forming fibrinogen units resuks in the dissolution of fibrin structure. 

 Working on the lysis of fibrin clots by the action of streptococcal 

 fibrinolytic factor, Garner and Tillett (1934b) reported that they were 

 unable to detect significant evidence of proteolysis during fibrinolysis. 

 They also reported that if fibrinogen is incubated with bacterial 

 fibrinolytic factor for a brief period, the fibrinogen can no longer be 

 converted to fibrin upon the addition of thrombin. Apparently, the 

 serum lytic factor (protease) as contaminant in fibrinogen having been 

 activated by bacterial factor had produced a deep-seated change in 

 the fibrinogen molecule. 



Seegers, Nieft and Vandenbelt (1945), working with a fibrinogen 

 preparation yielding 96 per cent fibrin, found that when the fibrinogen 

 solution was allowed to stand at room temperature for 6 days it 

 completely lost its fibrin-forming property on treatment with throm- 

 bin. Apparently, a trace of inactive serum protease present as contami- 

 nant was activated by treatment with alcohol, or chloroform, etc. used 

 during the preparation of fibrinogen. The fibrin prepared from whole 

 fibrinogen by the action of thrombin was likewise allowed to stand 

 at room temperature until virtually all the fibrin had gone into solu- 

 tion. The decomposed solutions of fibrinogen and fibrin were dried 

 from the frozen state and then analyzed electrophoretically, and frac- 

 tionated chemically into a- and /^-components. Both fibrinogen and 

 fibrin decomposition products yielded these two derivatives. i^-Fibrino- 

 gen derivative, one of the two components, showed electrophoretic 

 properties similar to that of whole fibrinogen. It was heat coagulable 

 at 51°C., precipitable with ammonium sulfate and had an isoelectric 

 point near pH 5.5, which is the isoelectric point also of fibrinogen. 

 /3-Derivative of fibrinogen, present in smaller concentration, was non- 

 coagulable with heat, soluble in ammonium sulfate, and its isoelectric 

 point was pH 4.2. Despite the similarities between the a-derivative 

 and whole fibrinogen the former lacked the clot forming property, in- 

 dicating that degradation of both the fibrinogen molecule and the 

 fibrin structure had taken place. No data were submitted concerning 

 the other possible digestion products of smaller molecular weight. 



Christensen (1945) studied the extent of the digestion of fibrin 

 clot and fibrinogen by measuring: (a) the decrease in acid-precipitable 

 nitrogen; (b) the increase in acid-soluble "tyrosine"; (c) the libera- 



