212 ABIOGENIC ORGANIC-CHEMICAL EVOLUTION 



On the basis of his experiments J. S. Fruton^-^ has con- 

 cluded that the magnitude of Af depends on the nature of 

 the components taking part in the reaction and is, accord- 

 ingly, very variable, sometimes falling at low as 400 cal/mole. 

 Most syntheses of peptides are endoergic but in certain cases 

 they may be exoergic. Furthermore, Fruton points out that 

 a very promising way of increasing the yield of peptides is 

 by using reactions which lead to the formation of products 

 which separate out from the general solution by becoming 

 insoluble. This is what happens when, for example, glycina- 

 mide is converted to glycine anilide. In this reaction the 

 yield may be as high as 65 per cent. Fruton considers that 

 one of the fundamental ways in which the length of poly- 

 peptide chains may be further increased is by transpeptida- 

 tion and transamination reactions which occur without the 

 expenditure of much energy. 



In the scientific literature there have already accumulated 

 a number of more or less probable hypotheses as to the 

 sources of the energy needed for the synthesis of polypeptides 

 and the scheme of co-ordination of the energy exchanges in 

 the reactions. We may cite as an example the hypothesis 

 of F. Lipmann^^^ concerning the participation of trans- 

 phosphorylation of ATP, which is based on experiments 

 on the synthesis of glutathione. However, as we have pointed 

 out above, the co-ordination of these energy-exchange and 

 synthetic reactions presupposes the existence of a certain 

 organisation. It is perfectly applicable to protoplasm but not 

 to the primaeval solution of organic substances. In this case 

 it would seem far more rational to look for the immediate 

 sources of energy in the conditions prevailing in the sur- 

 rounding medium. The ideas put forward by S. E. Bresler"^ 

 are particularly interesting in this connection. Bresler con- 

 siders that the free energy taken up in the formation of 

 peptide bonds in aqueous solution might be provided by the 

 work done by external compression. He therefore carried 

 out his syntheses under pressures of the order of some 

 thousands of atmospheres and, according to his reports, he 

 actually synthesised peptide bonds in the presence of the 

 appropriate enzymes, obtaining polymers of amino acids of 



