Evolution of Photosynthetic Mechanisms 35 



in various ways. Aside from the more or less laborious and specific 

 methods involving special protective or activating groups, at least 

 two simpler methods, possibly applicable to primitive conditions, 

 have been successfully demonstrated in the laboratory recently. The 

 first involves heating amino acid mixtures in molten glutamic acid 

 together with some polyphosphoric acid to produce a mixed poly- 

 peptide resembling protein. 30 The second involves heating the amino 



— N— C— C— 

 I I 

 H H 



N — C-C— N— C— C— N 



I I I I II I 



H H H H H 



t 



♦r^V. H 



-c- 



II 

 



N 



FIG. 10. Protein structure. Simple structural principles. Variety of chemical re- 

 activity. 



acid in an aqueous ammonia solution to produce a polypeptide of 

 intermediate size. 37 



The proteins themselves can take on a specific structure which i> 

 shown in Fig. 10. The protein is a combination of amino acids, and 

 the helical structure is built in into the linear array of the amino 

 acids because of the particular arrangement of carbon, hydrogen, 



