CHLOROPHYLL AND HEMOGLOBIN 237 



has also been obtained from haemoglobin, the red colouring 

 matter of the blood, and a connexion between haemoglobin 

 and chlorophyll is thereby established. 



The relationship between this hsematinic acid imide and 

 haemoglobin is as follows : — 



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:!: and haematoporphyrin on oxidation yield the 

 haematinic acid imide mentioned above. 



Another link between chlorophyll and haemoglobin is sup- 

 plied by the fact that Willstatter and Asahina § have obtained 

 from chlorophyll by reduction three pyrrole derivatives : — 



C,HX = CCH,\ C.,H5C = CCH,\ C.,H,C = CH \ 



- '1 ')NH " I "Vh ■■ I >H 



CH3C = CCH3/ CH3C = CH / CH3C = CCH3/ 



Phyllopyrrole Haemopyrrole Iso-hasmopyrrole 



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 11 : — 



In this connexion compare the formula assigned to 

 Aetiophyllin (page 233). 



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

 t It should be noted that chlorophyll derivatives free from magnesium are by 

 analogy called porphyrins: cf. Phylloporphyrin, etc. 



t-Kiister: " Zeit. physiol. Chem.," 1S99, 28, i ; 1900, 29, 185. 

 § Willstatter and Asahina : " Annalen," 1911,385, iSS. 

 II Willstatter and Fritzschc : id., 1909, 371, 33. 



