THE CHLOROPLAST ENZYMES 



381 



Table 14.VIII 

 Carbonic Anhydrase in Leaves (after Neish) 



the leaf pulp gradually loose their phytol led to its discovery. When 

 leaves rich in chlorophyllase (for example, those of Heracleum spondylium) 

 are kept in aqueous methyl alcohol for several hours, chlorophyll is 

 converted into methyl chlorophyllide, which forms crystaline aggregates 

 in the cells (Borodin's and Monteverde's "crystalline chlorophyll"). 



Grass, nettle, and certain other plants are poor in chlorophyllase, and 

 are therefore particularly suitable for the extraction of intact chlorophyll. 



The enzyme can be used both for the preparation of alkyl chloro- 

 phyllides from chlorophyll and for the reverse reaction, the synthesis of 

 chlorophyll from alkyl chlorophyllide (or free chlorophyllin) and phytol 

 (Willstatter and Stoll 1913; Fischer and Schmidt 1935). 



Meyer (1930) studied chlorophyllase in Noack's laboratory. His enzyme prepara- 

 tions were made by extracting chlorophyll with dry acetone from centrifuged chlorophyll- 

 protein precipitates. The remaining colorless material was used for the hydrolysis of 

 chlorophyll and its derivatives in buffered aqueous acetone solutions of known pH. 

 An optimum of activity was found at pH 6. The enzyme acts equally strong on chloro- 

 phyll and on pheophytin, but about four times more slowly on allomerized chlorophyll. 

 Pure chlorophyll a is hydrolyzed 18 times more quickly than the pure b component. 



Preparations which are hberated from electrolytes by protracted washing lose the 

 greater part of their activity, which can be restored by the addition of salts, e. g., lithium 

 chloride, potassium chloride, cupric chloride, iron lactate, etc. Ferrous salts have an 

 effect even in a dilution of 0.001 mole per Uter. Addition of potassium cyanide to 

 electrolyte-containing preparations has no effect; but its addition to preparations from 

 which salts have been removed by washing causes a complete loss of activity. The 

 enzyme is resistant to absolute alcohol, even when hot, and to hydrochloric acid, but 

 is easily deactivated by ammonia. 



Meyer gives tables of the relative chlorophyllase content of different 

 plants, as well as its variations with age, season, etc. The preparation 

 of the enzyme from Noack's "chloroplast matter" precipitates (cf. also 

 Krossing 1940) indicate its presence in the chloroplasts; but white parts 

 of variegated leaves, and even certain roots, also contain chlorophyllase. 



