184 IMMUNO-CATALYSIS 



ascaris. Weinland (1903) isolated a substance from ascaris capable of 

 inhibiting both peptic and tryptic activity. He concluded that the 

 inhibitor acted by combining with the enzymes and that its function 

 was to prevent the destruction of the parasite by the host's digestive 

 juices. In the Hght of the findings of Fermi, Northrop and others, 

 discussed above, that "hving" cells or living protein molecules are not 

 attacked by proteolytic enzymes, Weinland's conclusions do not ap- 

 pear to be acceptable. Furthermore Sang's (1938) findings throw a 

 different light on the subject. Though Sang's experimental findings 

 corroborate the principal part of Weinland's findings, his data suggest 

 that the antipeptic and antitryptic substance of ascaris is a protease.* 

 He extracted it by grinding the cut up worms to a mass in a mortar 

 and extracted the ground mass with water for 3 days under sterile 

 conditions. The extract filtered through a Berkefeld filter was found 

 to be stable on boiling in acid solution. In fact the proteolytic activity 

 of the preparation increased by coagulating and removing the ex- 

 traneous proteins. On boiling from five to 36 hours the activity was lost 

 with the disappearance of the biuret reaction. It was completely pre- 

 cipitable by less than half saturation with ammonium sulfate. This, 

 with its ready diffusibility through parchment and its precipitability 

 by 70 to 80 per cent alcohol made it probable that this substance was 

 an enzyme of small molecular weight or was associated with a sub- 

 stance of the order of a primary albuminose. Sang called this substance 

 ascarase. 



This preparation exercised proteolytic activity on casein and pep- 

 tone in buffered reaction systems at an optimum pH of 5 to 7. Since 

 it was also found that the maximum inhibition of trypsin by this sub- 

 stance lay within the same pH range. Sang held it probable that the 

 two enzymes combine with each other at a pH range of their maximum 

 activity as they would with their normal substrates. This combina- 

 tion between the two enzymes was rapidly formed and easily reversible. 

 It was found that ascarase was partly destroyed by standing in solution 

 at neutrality, while in its combination with trypsin it was not destroyed. 

 The study of the kinetics of numerous reaction systems revealed that 



* According to Hamed and Nash C1932) extracts of Ascaris lumhricoides contain 

 both a trypsin inhibitor and a proteolytic enzyme of optimal activity at pH 8 and 

 37.5 °C. They found that this trypsin inhibitor (free from the worm proteinase) 

 protected isoelectric insulin at pH 8 and 37.5°C. against the proteolytic action of 

 strong pancreatic solutions. 



