40 The Nature of Biological Diversity 



this reaction, a certain amount of orthophosphate is converted into 

 pyrophosphate. The reaction may be written as follows: 







*(Fe ++ + H 2 P0 4 ~ > (Fe n -0-P-CT +H + 



OH 







> CFe m -0-P-0 + HO- + OH - 



I 

 OH 





 II II II 



0~-P-0H ► CFe m -0H + ~0-P— 0-P-OH 



1 II 

 ^H-0 H-0 



* The half circle around the iron symbol is introduced to represent any other 

 coordinated atoms or groups. 



I believe this to be evidence of the primitive way in which the highly 

 evolved oxidative phosphorylation which takes place today began. 

 The complexing of phosphate by ferrous iron, followed by the with- 

 drawal of an electron from the ferrous iron to make ferric iron, the 

 elimination of a water molecule to make pyrophosphate, reduction of 

 the ferric iron to ferrous, completes a cycle for the formation and the 

 liberation of the pyrophosphate linkage. This is now demonstrated 

 in a simple system, and I think it will not be long before we will be 

 able to demonstrate it in the highly evolved iron systems that are 

 used in oxidative phosphorylation, both in plants and in animals, and 

 which are also used in photosynthetic phosphorylation probably in a 

 similar manner. 



You can see here a driving force which will give rise to the 

 porphyrin molecule. The driving force is the peroxide present in the 

 ocean and the usefulness of transforming orthophosphate to pyro- 

 phosphate in aqueous solutions so the pyrophosphate can then be 

 used to assist the combination of amino acids to make proteins. This 

 was the evolutionary sequence which gave rise first to the porphyrin 

 and second to a mechanism for manufacturing pyrophosphate. 



Coupling 



As yet we have suggested no mechanism for using light to perform 

 these processes. All that would be required in the later stages is to 



