648 XIV. PYRROLE PIGMENTS IN EVOLUTION 



chloroplasts acting in photosynthesis, the cytochrome system, 

 catalase and peroxidases, and perhaps the "Pasteur enzyme," acting 

 in respiration. In yeast and many bacteria, free porphyrins are 

 synthesized, but the cytochrome system and catalase are also present. 

 Fischer and Borst and Konigsdorffer (332,834) considered that the 

 formation of free porphyrin in yeast and in porphyria patients was 

 an evolutionary atavism. There is no sound evidence for this theory, 

 since the synthesis of free porphyrins of type I, or of porphyrins, 

 such as the coproporphyrins which do not combine in vivo with iron, 

 is always accompanied by the formation of hematin compounds con- 

 taining protoporphyrin IX. 



2. PALEONTOLOGY OF PORPHYRINS 



In 1933 Fikentscher (756) isolated porphyrin derivatives from the 

 fossilized excrements (coprolites) of crocodiles. Treibs {282If.-2826) 

 found porphyrins of chlorophyll {e.g., desoxophylloerythrin) as well 

 as of hemoglobin derivation (meso-, mesoetio-, and deuteroetio- 

 porphyrins, i.e., largely decarboxylated porphyrins) in petroleum, 

 oil shales, earth waxes, asphalts, and coals. While the crocodile 

 coprolites are of early eocene age (beginning of the tertiary period) 

 and thus about 25-30 millions of years old, porphyrins have also 

 been extracted from far older deposits, the oldest being the lower 

 silurian. Only free porphyrins have been preserved; the more sensitive 

 hematin compounds of the blood seem to have largely undergone 

 destruction. Vanadium complexes have been found, but they are of 

 secondary origin, vanadium frequently occurring in these deposits. 

 It may be mentioned that the so-called "vanadium-hemochromogen" 

 of the Tunicata has no relation to porphyrin compounds, though it 

 may be related to bile pigments {3006). 



These findings are of interest for the theory of formation of these 

 deposits, both with regard to the organisms from which the deposits 

 originated {e.g., plants for petroleum) and to the conditions to which 

 the deposits have been exposed. The presence of decarboxylated por- 

 phyrins, for instance, gives a clue with regard to the temperature of 

 the process, while that of desoxophylloerythrin indicates reducing 

 conditions. They are also of interest as proof that the nature of the 

 essential biological catalysts many millions of years ago did not 

 differ from that of the pyrrole compounds found in present-day 

 organisms. 



