368 ENZYMES 



chloride. The h"quid is filtered off and placed in a dialyser ; the 

 salt having thus been removed, an excess of alcohol is added 

 and the precipitate filtered off. The precipitate is washed with 

 alcohol and may be dissolved in water before use. 



For commercial purposes the enzyme is prepared as fol- 

 lows : * Castor-oil seeds are ground up with water and then cen- 

 trifuged ; the resulting emulsion, which contains castor oil, 

 proteins, and the enzyme, is then allowed to ferment at a 

 temperature of 24°, whereby a scum containing the ferment 

 rises to the surface and can be separated from the aqueous 

 layer. This scum is then allowed to act upon the molten fat 

 in the presence of water and a little manganese sulphate as a 

 catalytic agent. 



The following experiments described by Connstein, Hoyer, 

 and Wartenberg, may be taken as an illustration of the process 

 on a small scale. 



Five grams of castor-oil seeds are macerated with lO c.c. 

 of water containing 0*2 gram of acetic acid and 01 gram of 

 chloral hydrate. After twenty-four hours it is found that about 

 58 per cent of the fat originally present has been hydrolysed. 



To show that the enzyme is not destroyed by extracting 

 the fat from the seeds by means of ether, i -5 grams of seeds 

 which had been so extracted were ground up with 75 grams 

 of cotton-seed oil and 15 grams of N/io sulphuric acid. In 

 forty-four hours 82 per cent of the oil had been hydrolysed. 



QUANTITATIVE DETERMINATION OF THE ACTIVITY OF LIPASE. 



The activity of this enzyme is conveniently studied by 



allowing it to act on ethyl butyrate and observing the amount 



of acid liberated by titration or by conductivity measurements. 



DIASTASE 



Diastase is one of the commonest of enzymes ; in fact it 

 may be regarded as being universally present in the higher 

 plants. The amount present in any particular organ varies 

 according to the conditions obtaining ; thus when the tem- 

 perature and other factors are most favourable for growth and 

 for the germination of starchy seeds, diastase is much more 

 abundant than when growth and germination are sluggish. 



* Cf. Hoyer: " Der Seifenfabrikant," 1905, 25, No. 27. 



