642 



XIII. HEMOGLOBIN AND PORPHYRIN SYNTHESIS 



to form hemoglobin, are supposed to constitute one coordinated 

 process of hemoglobin synthesis; this has also been assumed by 

 Rimington. A slight excess of reaction 2 over reaction 3 allows a 



AC P 



C^N^ 



ii: 



M P 



C^N^ 



[91 



uroporphyrin I 



porphobilinogen i ► uroporphyrin III 



(+CH20) i im 



■-. c C I 



coproporphyrin I 



) > coproporphyrin III 



^ protoporphyrin IX 



hemoglobin 



Figure 8 



slight formation of coproporphyrin I by autocondensation of C, 

 while a still smaller amount of coproporphyrin III is synthesized by 

 condensation of a small fraction of D with C. 



