CHLOROPHYLL AXD THE CHLOROPLASTS 361 



Chlorophyll a C.-,HT-.OnN4Mg. 



( MgN,C.,,H.oO)COOCH:, . COOCooH,., 



Chlorophvl! /' C55H,„OeN,Mg. 



(MgN4C3,H2KO,)COOCH3 . COOC0H39. 



Chlorophyll a. C3,H,9N3Mg(NH . CO) (CO.CH,) (CO,C2oH39), with 



acid > phcTophytin a, C32H320N4(C02CH3) (CO2C00H39), with al- 



kaH > phvtochlorin e, Cs.HsoON^CCOaH) (CO^H). 



Chlorophyll /7, CaoHogOoN^MgCCOXHa) (COoC.oHan), with acid > 



phasophytin h, C3oH3o02N4(COoCH3) (CO2C00H39). . with alkali * 



phytorhodin g, C3oH3o02N4(C02H) (CO2H) . H.O. It has not been 

 possible to convert one component into the other by oxidation or reduction. 



The determination of the nature of the products obtained by the dis- 

 integration of the chlorophyll molecule necessitated a tremendous amount 

 of work and it is impossible to describe here the methods which are used 

 to separate the products or the physical and chemical properties of these 

 substances. For this information reference must be made to the very 

 voluminous original literature. It may aid, however, in obtaining a sur- 

 vey of the subject, to outline the relation between the different substances 

 and the formulae which have been ascribed to these. 



Mention has already been made of three methods which have been 

 used to break down the chlorophyll molecule, all of which yield different 

 products: 1, alkali hydrolysis, 2, acid hydrolysis and 3. the action of the 

 enzyme chlorophyllase. The latter, when acting on chlorophyll in alco- 

 hol solution, splits off phytol forming the methyl- or ethylchlorophyllids 

 from which in turn the free chlorophyllid may be obtained. These com- 

 pounds can be obtained in no other way. By elimination of magnesium 

 from these compounds through the action of acids, phc-eophorbids are 

 formed. The latter, in turn, may be formed from phaeophytin with 

 methyl or ethyl alcohol and hydrogen chloride, thus replacing the phytol 

 by a methyl or ethyl group. The relationship of these various compounds 

 and the manner in which they are obtained becomes evident from the 

 diagram describing the reactions of chlorophyll a. The reactions of chloro- 

 phyll h follow similar steps (see page 362). 



The action of alkalies on chlorophyll is somewhat more complex than 

 that of acids. Both chlorophyll a and h, on treatment with alkali give two 

 series of products ; the members of one fluoresce like chlorophyll, the 

 members of the other do not. Thus chlorophyll a with alkali yields 

 chlorophyllin a and isochlorophyllin a. Chlorophyllin (/, [MgCsiHogNg] 



(NH.Cb)(COOH).,, alkali ' 140" > glaucophyllin, MgC3iH32N4 



(COOH)2, with alkali 165° > rhodophyllin. MgC3iH32N4(COOH)2, 



with alkali 200° > pyrrophyllin, MgC3iH33N4(COOH). Isochloro- 

 phyllin a with alkali in the same manner yields compounds which are 



