DAVID SHEMIN 



aminolevulinic acid-5-C^^ as from glycine-2-C^*; 50 per cent 

 of the C^^ activity resides in the pyrrole rings and 50 per cent 

 in the methene bridge carbon atoms (see Figure 2) (29) . 



TABLE III 



Distribution of C^^-Activity in Protoporphyrin Synthesized from 

 5-Aminolevulinic Acid-5-C''* and from Glycine-2-C" (16,25) 



Molar activity (%) in fragments 

 of porphyrin synthesized from 



Fragments of porphyrin 



Protoporphyrin 



Pyrrole rings A + B (methylethyl- 



maleimide) 

 Pyrrole rings C + D (hematinic acid) 

 Pyrrole rings A + B + C + D 

 Methene bridge carbon atoms 



Also it can be seen from Table IV that the same C^* dis- 

 tribution pattern was found in protoporphyrin synthesized from 

 5-aminolevulinic acid-l,4-C'^ as from succinate-l,4-C^^; ten 

 carbon atoms are equally radioactive, 40 per cent of the G^'* 

 activity resides in pyrrole rings A and B, 60 per cent of the 

 activity resides in pyrrole rings G and D, and the carboxyl groups 

 contain 20 per cent of the G^^ activity (see Figure 4) (20). 



TABLE IV 



Distribution of C^^ Activity in Protoporphyrin Synthesized from 

 5-Aminolevulinic Acid-1,4-C'^ and from Succinate-1,4-C'^ (20) 



Molar activity (%) in fragments 

 of porphyrin synthesized from 



Fragments of porphyrin 



Protoporphyrin 



Pyrrole rings A + B (methylethyl- 



maleimide) 

 Pyrrole rings G + D (hematinic acid) 

 Pyrrole rings A + B + G + D 

 Garboxyl groups 



528 



