The Action of Enzymes on Hexosephosphate. 



419 



mined by titration of 1 c.c. with N/10 KOH, phenolphthalein as indicator. 

 In all experiments the term hexosephosphate is used to designate the 

 solution neutral to litmus. The extent of hydrolysis was in each case 

 ascertained by precipitating the liberated phosphate with magnesium citrate 

 mixture, igniting and weighing as magnesium pyrophosphate. All results, 

 as well as the concentration of the original hexosephosphate solutions, are 

 expressed in terms of magnesium pyrophosphate. 



The following enzyme preparations were employed : — 



(a) lipase from castor oil seeds ; (h) autolysed ox pancreas ; (c) emulsin ; 

 (d) zymin extract ; (e) autolysed yeast-juice. 



(a) Lipase from Castor Oil Seeds (Eicinus communis). — This was prepared by 

 extracting the freshly ground seeds Of Ricinus communis with ether until 

 fat free, and using the residue as the lipase preparation. It was found to be 

 highly active. 



The results of three experiments are given in the accompanying table, 

 which refers in each case to the following set of mixtures : — 



A. 0-3 grm. lipase + 3 c.c. N/5 acetic acid+15 c.c. water. 



B. „ „ „ +15 c.c. hexosephosphate. 



C. Same as B, but boiled before incubation. 



The experiments were carried out at 25° in presence of toluene (0*5 c.c), 

 and different hexosephosphate solutions were employed in each set of 

 experiments. 



No. 



Original 

 hexosephosphate 

 as Mg 2 P 2 7 . 



Time of 

 incubation 

 in hours. 



Free phosphate, 

 grm. Mg 2 P 2 7 . 



Phosphate 

 liberated, 

 B-C. 



A. | B. 



G. 



1 



-5835 



24 







-1259 



-0428 



-0831 







48 







-1836 



-0320 



-1516 



2 



-5665 



120 







-2746 



-0416 



-2330 



3 



-6274 



240 







-3655 



-0359 



-3296 



It is seen that the preparation had a considerable hydrolytic action on the 

 hexosephosphate. 



(b) Ox Pancreas. — The fresh ox pancreas, freed as far as possible from con- 

 nective tissue, was allowed to undergo autolysis for four days under toluene 

 at 37°. The liquid was then filtered through a coarse muslin cloth to 

 remove any undigested pancreas, and the filtrate used in the experiments. 



