MACROMOLECULES 



121 



Per Fe+++OH + HOOR ^ Per Fe+++OOR + H^O 



(brown) (green) 



Per Fe+++OOR ^ Per Fe+++OOR 



(green) (pale-red) 



Per Fe+++OOR + AH2 -> Per Fe+++OH + ROH -f A 



Another hydroperoxidase is catalase. This is a particular type of peroxi- 

 dase which can decompose hydrogen peroxide in the absence of a second 

 substrate : 



2 H0O2 -^ 2 H2O + O2 



300 



400 500 



m a 



600 



Fig. 21 (H. Theorell) — Absorption spectrum of crystalline peroxidase. 



(b) Chlorophylls and Chlorophyll-proteijis 

 Chlorophylls-^ and b are extracted from leaves by acetone, along with 

 other pigments. The addition of an equal volume of petroleum ether and a 

 small amount of water, to this extract, removes most of the chlorophyll. 

 From this petroleum ether solution it is possible, by extraction with 

 aqueous methanol, to remove most of the xanthophyll and a little of the 

 chlorophyll-6. Extracting with water several times, in this way, one finishes 

 by precipitating the chlorophyll, which is collected on a filter and its two 

 constituents separated, by utilizing the fact that chlorophyll-fl is more 

 soluble in petroleum ether, and chlorophyll-6 is more soluble in methyl alcohol. 

 The chlorophylls are methylphytol esters of the chlorophyllines, which 

 are the corresponding acids. These are neutral substances containing 

 magnesium in a non-ionic form. A hydrolase, called for this reason chloro- 

 phyllase, splits off from chlorophylls a C-20 (with one double bond) ali- 

 phatic alcohol which is a diterpene derivative named phytol (see p. 31). 



