238 



Willst'dttcr's Rcscarches on Chlorophyll 



[Jan. 



in all 5 gm. of the pigment, then 60 gm. of this dry material is said 

 to be an m/io enzyme; that is, o.i of the material which would con- 

 tain 3 gm. of Chlorophyll. The coiirse of the reaction may be fol- 

 lowed by estimating the amount of free chlorophyllide colorimet- 

 rically after extraction with w/50 potassium hydroxide sol., by de- 

 termining the phytol number, or by Splitting off the methyl and 

 ethyl groups with hydroiodic acid according to Zeisel. 



Since the enzyme is used in the form of a powder, the reaction 

 proceeds faster when the Suspension is stirred. An attempt to 

 apply the law for monomolecular reactions to the enzyme in alco- 

 hohc Solution, using the formula 



K. = —In > 



t a — u 



gave values for k which decreased considerably as the reaction 

 proceeded. 



N/io enzyme at 25° C, 500 c.c. of extract containing 1.8 gm. of Chlorophyll. 



This may be due to a co-enzyme or activator, which decreases the 

 rate of reaction; or it may be that during the action the enzyme is 

 gradually destroyed or its activity decreased. This is seen in the 

 following experiments. 



The enzyme was allowed to act on Chlorophyll for periods of 

 two and one-half, five and ten hours, and then was used for fresh 

 Solutions of Chlorophyll. The results are given in the appended 

 table : 



