CHEMICAL PATHWAYS 



121 



processes will certainly throw light upon the real function of soluble RNA 

 and upon the mechanism of amino acid transfer to the ribosome. 



It will be important also to know a little better the conditions for coapta- 

 tion between polynucleotides, a promising field of studies opened by the 

 work of Rich (1959). 



A completely unexplained fact is the necessity of a complete assortment 

 of amino acids for RNA synthesis. The fact that analogues of amino acids 

 inhibit RNA formation is another reason to believe that the individual 

 amino acids have a specific function in RNA synthesis. There is indeed an 

 intriguing reciprocity between the requirement for amino acids in RNA 

 synthesis and the requirement for precursors of RNA in protein synthesis. 

 This led several workers to the suggestion that RNA and protein might be 

 assembled from common precursors, visualized as some kind of nucleotide 

 amino acid compounds (Gros and Gros, 1957; Yeas and Brawerman, 1957; 



v. ... v.... v.- V..- 



Growing 



peptide 



chains 



Tcmplot* 

 surface 



Direction o1 chain growth 



Fig. 32. 



Pardee et ah, 1957; Spiegelman, 1957). The recently discovered inter- 

 actions between amino acids and nucleoside triphosphates (Beljanski, 1960) 

 might prove of great interest in this respect. The relation between amino 

 acids and the synthesis of RNA might be the key to the template mechan- 

 ism for the synthesis of proteins and nucleic acids. Interesting attempts at 

 formulating in chemical terms template processes taking this idea into 

 account have been made by Simkin and Work (1957), Kiepal-Kochanska 

 (1958), Michelson (1958). Raacke (1958) has proposed a more elaborate 

 process which features attachment of the carboxyl activated amino acids to 

 the template by their — NH2 groups, and which has the merit of making 

 predictions and suggesting experiments. Future research will tell the value 

 of these various hypotheses. 



