872 



PHYSIOLOGY 



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

 following formula: 



Oiyptopyrrole 



CH 3 



Phyllopyrrole 



CH 6 C 2 H 6 



NH 



NH 



Isohaemopyrrole 



CH 3 



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, aetioporphyrin. 



It is interesting that haematoporphyrin also can be readily converted into aetio- 

 porphyrin. On treatment with pyridine and alcoholic potash, it is converted into 

 haemoporphyrin and this heated with soda lime gives aetioporphyrin (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, aetioporphyrin and haematoporphyrin are both built up of 

 four substituted pyrrol rings. 



Thus haematoporphyrin has the following structural formula : 



CH 3 .C CH 



N 



OH.C 2 H 4 .C C 



COOH.C 2 H 4 



C CH 



G= C.CH 3 



HN 



C= C.C. 2 H 4 .COOH 

 \ 



CH 8 . 



and the same worker suggests the following formula for haemin : 



CH^C 



CH 



CH^C 



COOH.C 2 H 4 .C= C 

 CH 8 . 



C.C 2 H 4 .COOH 



THE SYNTHESIS OF THE BLOOD PIGMENTS. Chemists have not 

 yet succeeded in the artificial formation of haematoporphyrin. Given 

 hsematoporphyrin however, evidence has been brought forward both by 

 Menzies and Laidlaw of the possibility of forming artificially both hsematin 

 and haemoglobin, or some substance indistinguishable from the latter. 



