DIASTASE 477 



The optimum temperature of spermatolipase is 35° ; in 

 a water fat emulsion a temperature of 50° C. is lethal. The 

 optimal reaction of spermatolipase is at Pjj 47 ; at Pj, 6 it is 

 quite inactive ; blastolipase, on the other hand, shows a much 

 wider range from 47 to 6-8 ; even at Pg 8 its activity is measur- 

 able. Further, blastolipase is much more stable in the dry 

 condition, and has a greater synthetic power than sperma- 

 tolipase. For the measurement of the lipolytic activity of 

 enzyme preparations, Willstatter and Waldschmidt-Leitz have 

 devised certain standards of reference termed phytoUpase units 

 and the phytolipase value, the latter being the number of 

 phytolipase units in one centigram of the preparation. For 

 details the original papers should be consulted. 



DIASTASE (AMYLASE). 



The term diastase must be regarded as generic : it includes 

 a number of enzymes which are characterized by their power 

 of attacking starch dextrin and like substances ; they are of 

 wide distribution and those from different sources have not 

 precisely the same characteristics. The amount present in 

 any particular organ varies according to the conditions 

 obtaining ; thus when the temperature 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 slow. Also, the amount of diastase is 

 always greater in starch leaves than in sugar leaves and the 

 same holds for insolated leaves containing much starch, as 

 compared with shaded leaves containing little or no starch.* 

 The abundance of amylase in regions of active growth suggest 

 to Sjoberg f that amylase also is concerned in synthethic 

 activity. 



It has already been stated (p. 155) that the action of 

 diastase on starch is twofold and that it is possible to distin- 

 guish between a liquefying action on the one hand and a 

 saccharifying action on the other. 



* Eisenberg : " Flora," 1907, 97, 347. 



t Sjoberg : " Biochem. Zeit.," 1923, 142, 274. 



