SOME PHYSICAL PROPERTIES OF PTYALIN. 155 



SOME PHYSICAL PROPERTIES OF PTYALIN. 



DAVID J. LEVY. 



The physical properties of ptyalin, which it is our purpose to consider, 

 are (1) the removal of ptyalin from saliva on filtration through hard- 

 ened filter paper, due to fixation; (2) the dialysis of ptyalin through the 

 collodium sac; and (3) the removal of ptyalin from solution by filtration 

 through the collodium sac, due to mechanical retention. Before enter- 

 ing into a description of the experiments which have demonstrated the 

 first named of these properties, it will be well first to review the literature 

 on the subject of the paper filtration of enzymes. 



Musculus, in 1874, called attention to the fact that solutions of urase 

 are considerably weakened as a result of their filtration through paper. 

 This was explained by Lea on the ground that urase is not a soluble 

 ferment. Miquel, 1898, however, demonstrated the solubility of this 

 enzyme. 



Wortmann (1890), tested the filtered aqueous extracts of green leaves 

 for diastatic activity, and the filtrates which did not invert starch, he 

 declared free from diastase. This elicited from Brown and Morris the 

 following : 



''The protoplasm often parts with its enzyme with difficulty, and 

 it is often impossible to obtain from such a preparation a clear filtrate 

 which has any hydrolyzing action, although an energetic^ hydrolysis 

 may be produced by contact with the tissue itself, or by the employment 

 of a turbid filtrate containing the finely divided tissue in suspension." 

 In evidence they cite the following experiment : 



The leaf of Helianthus tuberosus was extracted by the prolonged 

 action of water on the crushed and pounded fresh leaf. With chloro- 

 form antisepsis the diastatic activity of 10 g. of dried leaf of Helianthus, 

 acting by direct contact, bore a ratio to the activitj^ of the filtered ex- 

 tract of 10 g. of the same leaf of 3.78 to .53. 



Vines (1891) found that the turbid extract of green leaves when 

 merely strained was much more active than the clear extract obtained 

 by filtration. 



Brown and Herron (1893) stated that' the clear filtered, aqueous infu- 

 sion of the small intestine had but a slight action on starch, while con- 

 tact with the tissue itself produced pronounced hydrolysis, 



Kastle and Loeveuhart (1900), working on lipase, found a marked 

 decrease of lipolytic activity on filtration, both of aqueous and of gly- 

 cerin extracts of liver and of pancreas, and of Parke, Davis & Co.'s pan- 

 creatin. Before filtering, 1 c.c. of 10 per cent, liver extract was found 

 to hydrolyze 6.28 per cent, of ethyl butyrate in fifteen minutes at 40°. 

 After repeated filtration through the same paper, it hydrolyzed only 

 2.7G per cent. 



In order to determine whether or not ptj'alin could be removed from 

 saliva by filtration, the following experiment was carried out: 



Twenty c.c. of saliva, collected by mastication of paraffin, were 



