= 76 = 



Enzymatic Oxidation of Chlorophylls in Leaves 



Tffhen the leaves of many plants are killed with anesthetics or 

 by grinding, so that the oxidative systems are not destroyed, the 

 chlorophylls are partially oxidized yielding additional green pig- 

 ments5»-^-'-s5. This effect is particularly conspicuous when the 

 chopped, yo\mg, green leaves of barley are permitted to stand for 

 a day or two with twice their weight of acetone„ The pigments, 

 then extracted from the leaves with methanol and petroleum ether 

 and separated by chromatography in a column of powdered sugar, pro^ 

 vided a chromatogram like that shown in Figure IIIjl6o An oxidation 

 product of chlorophyll b separated just above the neoxanthin zoneo 

 An oxidation product of chlorophyll a separated with and just below 

 the chlorophyll b„ This a oxidation product and the chlorophyll b 

 were recovered, adsorbed in another column of powdered sugar and 

 separated by washing with benzene o Under these conditions, the a^ 

 oxidation product was sorbed above the chlorophyll b^o Each oxidation 

 product exhibited spectral absorption properties like those of the 

 chlorophyll from which it was derivedo But each oxidation product 

 gave a green phase test whereas the recovered chlorophylls gave yel- 

 low phase tests with strong alkalieSo 



The same oxidation products were isolated after barley leaves 

 had been treated with methanol, with ethanol and with ethyl ethero 

 These oxidation products were also found among the allomerization 

 products of the chlorophyllso (See next sectiono) 



Allomerization of Chlorophylls 



It has long been known that chlorophylls a and _b when dissolved 

 in absolute methanol and permitted to stand in air yield the so-called 



