576 



Messrs. E. Beard and W. Cramer. 



The invertase was prepared from yeast obtained from Distillers Co., Ltd., 

 Edinburgh, by two different methods : — 



(1) Preparation of Invertase from Fresh Yeast (called "Invertase F" in the 

 following Tables). — A weighed quantity of yeast was added to a measured 

 volume of chloroform water. The mixture was kept at a temperature of 38° 

 for 27 hours or longer. It was then filtered. The proteins were removed 

 from the filtrate with kaolin. The second nitrate was a clear yellow liquid, 

 which was used as the solution of the ferment. 



(2) Preparation of Invertase from Dried Yeast (" Invertase D " in the 

 following Tables). — Fresh yeast was pounded with distilled water and washed 

 three times by decantation. It was then collected in a Buchner funnel, 

 washed with alcohol and ether and spread in a thin layer on a glass plate. It 

 was completely dried in a vacuum desiccator. When dried the material was 

 ground in a mortar, placed in an oven at 40° and gradually warmed during 

 half an hour up to 100°. The brown powder then obtained was kept in a 

 stoppered bottle. When a solution of invertase was required, weighed 

 amounts of the brown powder were added to chloroform water and kept for 

 about 24 hours at a temperature of 38°. After filtration a clear yellow liquid 

 was obtained, which represented a solution of invertase. 



Eight different invertase preparations, all of which were strongly active, 

 were used in these experiments. In the Tables the various ferment preparations 

 are designated (1) by the letter D or F, indicating whether they have been 

 prepared from dried or fresh yeast respectively, (2) by the date of their prepara- 

 tion, and (3) by the percentage of yeast (fresh or dried) used with reference to 

 chloroform water. 



It was found that increasing the surface led to a distinct retardation in the 

 inversion of cane sugar by invertase if the concentration of the substrate was 

 relatively high, and that of the ferment relatively low. With a high ferment 

 concentration the retarding effect was not noticeable. The following 

 experiments are given as examples : — 



Experiment A. 23.7.14. Invertase F, 22.7.14, 100 per cent. 

 Sucrose solution 19 6 per cent. Temperature 18°. 50 c.c. sucrose : 



Hours. 



+ 5 c.c. invertase. 



+ 1 c.c. invertase. 



+ 0'2 c.c. invertase. 



Control. 



With beads. 



Control. 



With beads. 



Control. 



With beads. 





 22 

 47 

 96 



+ 11 -88 

 - 3-21 



+ 11-88 

 - 3 21 



+ 12 -93 

 + 4-93 



- 0-25 



- 3 16 



+ 12 -93 

 + 5-13 



- 0-03 



- 3-08 



+ 13 -02 

 + 11 -06 

 + 9-03 

 + 5-80 



+ 13 -02 

 + 11 -78 

 + 9-71 

 + 7-09 



