CHLOROPHYLL 



323 



Haemoglobin is readily hydrolysed by dilute acids or 

 alkalis with the formation of haematin ; this latter substance 

 contains iron, which can, however, be readily removed by 

 treatment with hydrogen bromide in acetic acid solution,* 

 giving an iron-free compound haematoporphyrin ; f both 

 haematin J and haematoporphyrin on oxidation yield the 

 haematinic acid imide mentioned above. 



Another link between chlorophyll and haemoglobin is 

 supplied by the fact that Willstatter and Asahina § have 

 obtained from chlorophyll by reduction three pyrrole deriv- 

 atives — 



C^HjC = CCH3 



\ 



CH3C=CCH3- 

 Phyllopyrrole 



NH 



CgHjC = CCHg 



CH3C = CH / 

 Haemopyrrole 



C2H5C = CHx 



>NH 



i /NH 



CH3C = CCH3/ 



Iso-hsemopyrrole 



one of which, haemopyrrole, has also been obtained by the 

 reduction of haematoporphyrin. 



With regard to the manner in which the magnesium or iron 

 are respectively united to the complex molecules of chloro- 

 phyll and haemoglobin, the following skeletons, involving the 

 assumption of subsidiary valencies, according to Werner and 

 others, have been suggested || :■ — 



/ 



)N 



C 



^N — Mg' 



N 



y 



•N: 



Chlorophyll 





)N 



/ 



C 



^N — Fe' 



N' 



•Nc 



CI 

 Haemin ^ 



^C 



c 



* Nencki and Zaleski : " Zeit. physiol. Chem.," 1900, 30, 423. 

 f It should be noted that chlorophyll derivatives free from magnesium 

 are by analogy called porphyrins : cf. Phylloporphyrin, etc. 



I Kiister : " Zeit. physiol. Chem.," 1899, 28, i ; 1900, 29, 185. 

 § Willstatter and Asahina : " Annalen," 191 1, 385, 188. 

 |] Willstatter and Fritzsche : id., 1909, 371, 33. 

 ^See also Kuster : "Zeit. physiol. Chem.," 1920, no, 93. 



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