THE RED BLOOD-CORPUSCLES 



829 



The hsemopyrroles, according to Willstatter are three in number and have the 

 following formula : 



Cryptopyrrole 

 CH 3 ,C 2 H 5 



H 



\x 



NH 



|^2-"-{ 



!CH 3 



Phyllopyrrole 

 CH 5 C 2 H 5 



CH 3 



Isohsemopyrrole 

 CH 3 



CH 3 



CH 3 



NH 



\/ 

 NH 



H 



The same substances can be obtained from the chlorophyll of plants. On treatment 

 with acid chlorophyll loses magnesium, and is converted into phacophytin. From 

 this three COOH groups can be split off leaving a substance setioporphyrin. 



It is interesting that hsematoporphyrin can be readily converted into the same 

 substance. On treatment with pyridin and alcoholic potash it is converted into 

 hsemoporphyrin, and this heated with soda lime gives setioporphyrin (C 31 H 36 N 4 ). 

 Thus the same group forms the basis both of the substance which is responsible in the 

 plant for the assimilation of carbon from carbon dioxide, and of the pigment which 

 in the animal is the carrier of oxygen between the tissues and the surrounding medium. 

 According to Willstatter, setioporphyrin and hsematoporphyrin are both built up of 

 four substituted pyrrole rings. 



Thus hsematoporphyrin has the following structural formula ; 



CH 3 .C 

 OH.C 2 H 4 . 

 COOH.C 2 H 4 < 



CH 3 J 



and the same worker suggests the following formula for hsemin : 



CH S C 



COOH.C 2 H 4 .C 



CH 3 .C 



.C 2 H 4 .COOH 



THE SYNTHESIS OF THE BLOOD-PIGMENTS. Chemists have not 

 yet succeeded in the artificial formation of hsematoporphyrin. Given 

 hsematoporphyrin, however, evidence has been brought forward both by 

 Menzies and Laidlaw of the possibility of forming artificially both haematin 

 and hgemoglobin, or some substance indistinguishable from the latter. 



