1912.] 



The Action of Enzymes on Hexosephosphate. 



421 



A. 5 c.c. zymin extract +15 c.c. water. 



B. „ „ +15 c.c. hexosephosphate. 



C. Same as B, but zymin extract boiled. 



Original hexosephosphate = - 6274 grm. Mg 2 P20 7 . 



After incubation, free phosphate in — 



A = 0-0625 



B = 01618 



C = 0-0910 



Phosphate set free by enzyme = 0-0708 „ 



(e) Autolysed Yeast-juice. — A sample of yeast-juice which had been allowed 



to remain at 0° for a fortnight was used. It was found to be incapable of 



fermenting glucose. 



The following mixtures were incubated at 25° for 24 hours in presence of 



toluene, and the free phosphate estimated : — 



A. Autolysed yeast-juice 25 c.c. + 10 c.c. water. 



B. „ „ + 10 c.c. hexosephosphate. 



C. As B, but boiled yeast-juice employed. 



Original hexosephosphate = 0-3776 grm. Mg 2 P20 7 . 



After incubation, free phosphate in — 



A = 0-1389 



B = 0-2232 



C = 0-L409 



Phosphate set free by enzyme = 0'0823 „ 



Hexosephosphate is thus hydrolysed to some extent by autolysed yeast- 

 juice. This is in agreement with with the experiments of Harden and 

 Young, who showed that in actively fermenting yeast-juice most of the 

 phosphate was present in the combined form, but was gradually set free by 

 an enzyme hexosephosphatase, after the juice had lost its fermentative 

 activity.* 



An attempt was made to ascertain if hexosephosphatase could be isolated 

 from the autolysed yeast-juice : 50 c.c. of autolysed yeast-juice were added 

 with constant stirring to a mixture of 400 c.c. alcohol and 400 c.c. ether. 

 The white precipitate was filtered immediately at the pump, washed once 

 with ether, and air dried. A very small amount of a brownish sticky pre- 

 cipitate remained. This was dissolved in 50 c.c. of water and allowed to 

 stand overnight with a little toluene. It was then filtered through muslin, 

 and the solution thus obtained examined as to its hydrolytic properties 

 towards hexosphosphate. 



* ' Eoy. Soc. Proc.,' 1908, B, vol. 80, p. 299. 



