BIOCHEMICAL MECHANISMS 49 



hypothesis, is that of Chargaff et al. (1956). They analyzed the 

 chemical composition of the small ribonucleoprotein granules 

 which were isolated from microsomes after deoxycholate treatment 

 and ultracentrifugation, according to Littlefield et al. (1955). In 

 agreement with the template theory, they found two amino acid 

 residues for one nucleotide residue, and further showed that all of 

 the protein is linked to RNA in these small particles. 



Also in favor of the template hypothesis is the fact, reported by 

 Potter and Dounce (1956a, b), that alkaline digests of RNA from 

 various sources (yeast, mammalian tissues) contain amino acids or 

 small peptides attached to nucleotides. The amino acids and the 

 nucleotides might possibly be bound together by phospho-amide 

 linkages. 



Finally, it seems impossible to explain the recent findings made 

 in the field on tobacco mosaic virus reproduction by any theory 

 simpler than that of the template. In tobacco mosaic virus, RNA 

 acts as a specific model which determines the structure of the pro- 

 tein which is synthesized (Jeener, 1956; Fraenkel-Conrat, 1956; 

 Gierer and Schramm, 1956 and others). 



It will be an important task for the future to explain how RNA 

 might act in a template mechanism. At present, we have only clever 

 theories and hypotheses. Unfortunately, they are still based on so 

 little experimental evidence that it would be fruitless to go into 

 them here. 



References p. 50 J 54 



