CHLOROPHYLL AND THE CHLOROPLASTS 



363 



isomeric with the phylHns from chlorophyllin, znc, cyanophyllin, crythro- 

 phyllin and phyllophyllin. The splitting off of the last carboxyl group 

 IS accomplished with soda-lime ; this leads to the formation of setiophyllin, 

 MgCsiHgiNi. The isomeric phyllins, just mentioned, differ in the posi- 

 tion of the carboxyl group. Finally, setiophyllin, on treatment with acid, 

 loses magnesium with the formation of cCtioporphyrin C3iH3eN4. 



astiophyllin— 

 Ca^Hs.N^Mg^- 



with acid 



with MgCHsI 



-^stioporphyrin 

 — C31H36N4 



The structures of setioporphyrin and of astiophyllin are of great in- 

 terest for the chemistry of chlorophyll ; these are in all probability the 

 groups which are responsible for the characteristic properties of chloro- 

 phyll. It is also of interest because of the possible relation of chlorophyll 

 to the pigments of blood. That an intimate chemical relationship may 

 exist between these two pigments has been suggested by Marchlewski and 

 others.^^ These suggestions are based largely upon the similarity in con- 

 stitution of compounds derived from chlorophyll and those derived from 

 hemoglobin. Both chlorophyll and hemin may be regarded as derivatives 

 of jetioiX)rphyrin. The constitution of these com^x)unds has not been 

 definitely established; the following have been proposed by Willstatter 

 and Stoll: 



CH=CH 



CH. — C 



C.Hs — C— C 



CH 

 \ 



/ 



c — c 



N 



\ 



/ \ 



\ 



C2H5 — C — 



CHa — C = 



\ 



C- 



/ 



/ 



/ 



C — CH 



/ 



N / 



r ^ ^ 



/ -C 



N 



/ 



C 



I 

 CH3 



Mg 



/ 



C = C — C,H, 



N 



\ 



C = C — CH3 

 I 



CHa 



^tiophylHn C3iH34N4Mg 



" Marchlewski, "Die Chemie des Chlorophylls," 1909. Nencki, Ber. chetn. Ges., 

 29 '2877 (1896); 34, 997 (1901). Burgi and Tracewski, Biochem. Zett., 98, 256 

 (1919). Gregori'ew, 'ibid., 98, 284 (1919). 



