BIOCHEMICALLY IMPORTANT COMPOUNDS 209 



of desoxyribose phosphate from acetaldehyde and glyceralde- 

 hyde phosphate by Escherischia coli. 



The polydesoxyribose phosphate formed in this way com- 

 bined with ammonia, oxaloacetic acid, glycine and formyl 

 residues. Thus were formed the primaeval desoxyribose 

 nucleic acids (Fig. 14). 



Even for the biosynthesis of nucleic acids in living organ- 

 isms Roka's scheme is certainly no more than a very ingenious 

 hypothesis. We must regard with even greater reserve the 

 analog)^ between it and the processes which might have taken 

 place in simple aqueous solution of various organic com- 

 pounds in the primaeval hydrosphere. 



Let us suppose that we have demonstrated the possibility 

 that Gulick's phosphoguanidine or some other high-energy 

 compound could ha\e been formed on the surface of the 

 Earth under the influence of ultraviolet irradiation or at the 

 expense of the large amount of energy which is liberated 

 by the oxidation of substituted phosphines by oxygen. Even 

 so, the probability that the energy of the high-energy bonds 

 would be transferred particularly to the carboxyl groups of 

 amino acids or used for the special purpose of phosphorylat- 

 ing ribose or for the formation of polyphosphoric acid is 

 extremely slight under conditions of simple aqueous solution 

 of large numbers of organic compounds. This could only be 

 expected to occur regularly in the presence of pre-formed 

 organisms, which would lead to the strict co-ordination of the 

 different biochemical reactions in space and time. Such 

 organisation is inherent in protoplasm, but it cannot have 

 existed in the waters of the primaeval ocean, where the course 

 of events was solely determined by relatively simple thermo- 

 dynamic and kinetic laws. 



It may be reckoned that we shall succeed in proving the 

 possibility of the formation of complicated polynucleotides 

 in the primaeval hydrosphere in accordance with these laws 

 either in the way described or in some other way. It still 

 does not follow in the least that a similar primary origin 

 was possible for nucleic acids identical with those which are 

 essential for present-day living organisms. These nucleic 

 acids are characterised by a strictly determined sequence 

 of mononucleotides in their polynucleotide chains and this 



14 



