48o ENZYMES 



by extraction with water. The solution is concentrated in 

 vacuo at 30-40° C, and then treated with 2-5 times its volume 

 of 95 per cent alcohol. The precipitate is filtered off and dried. 

 The crude takadiastase may be purified by dissolving in water, 

 precipitating with ammonium sulphate, redissolving the pre- 

 cipitate in water, dialysing off the salts, and precipitating with 

 alcohol.* In addition to amylase, takadiastase contains in- 

 vertase, maltase, protease, lipase, sulphatase, together with a 

 number of other enzymes. f 



MALTASE. 



This enzyme has a wide distribution and may be expected 

 to occur wherever starch and maltose are significant in the 

 metabolism of the plant. Thus it obtains in the leaves of the 

 potato, beet, mangold, dahlia, sunflower, turnip and other 

 phanerogams % and also is widely distributed among the 

 moulds and yeast, which latter form the best source for its 

 preparation. The amount occurring in different yeasts is, 

 however, variable ; very little occurs in Sac char omyces marx- 

 ianus, and distillery yeast generally provides but a small 

 yield. It occurs also in the ungerminated barley grain and 

 in green malt, i.e. germinated barley dried without the appli- 

 cation of heat. In the ungerminated grain it is insoluble in 

 water and its presence can only be demonstrated by allowing 

 finely ground barley to act on maltose. § During germination 

 the insoluble maltase undergoes some change whereby it 

 becomes partly soluble. 



Maltase converts maltose into glucose ; it has a delicate 

 constitution, for which reason its presence is easily over- 

 looked. Maltase is readily destroyed by heat, alcohol, and 

 acid ; owing to its destruction by alcohol it is not found with 

 the diastase precipitated from aqueous solutions by this 

 reagent. Its optimal temperature is 40° C, and it is rapidly 



* Sherman and Tanberg : " J. Amer. Chem. Soc," 1916, 38, 1638. 

 t Nishimura : " Chem. Zelle Gewebe," 1925, 12, 202. 

 X Daish : " Biochem. Journ.," 1916, 10, 49. 



§Ling and Nanji : "Biochem. Journ.," 1923, 17, 593; Maquenne : 

 " Compt. rend.," 1923, 176, 804. 



