IX. METABOLISM 289 



active proliferation of cells should be associated with the vigorous, 

 synthesis of proteins. Spiegelman and Kamen (111) have suggested 

 that nucleoproteins are specific energy donors which make reactions 

 possible leading to protein and enzyme synthesis. They have found 

 that when protein synthesis is occurring in the presence of nucleopro- 

 tein containing P^^, this latter element is liberated from the protein, 

 while on the interruption of the synthesis by the addition of sodium 

 azide or dinitrophenol the liberation of P^"* is ceased, indicating the 

 occurrence of the decomposition of nucleic acids solely in case of 

 energy requirement. In addition, many facts are known suggesting 

 that a certain correlation exists between the synthesis of proteins, 

 particularly fibrous proteins, and the occurrence of phosphatase and 

 nucleic acids both in the cytoplasm and in the nucleus (112). Nucleic 

 acid in the cytoplasmic granules is considered to be involved in 

 protein synthesis, and it is known from the work of Brachet and his 

 colleagues (113) that these granules contain phosphatase. The tissue 

 in which protein synthesis appears to be most active is also particularly 

 rich in nuclear phosphatase. 



On the other hand, numerous synthetic reactions driven by an 

 influence of energy-rich phosphate bonds are known. Peptide formation, 

 the synthesis of urea, transmethylation from methionine, the syn- 

 thesis of a- and i3-keto acids of fatty acids, and the process of 

 bioluminescence appears to belong to this group (114). In most cases 

 of such reactions ATP is apparently involved ; and there are many 

 evidences that ribonucleic acid is intimately connected with protein 

 synthesis (29). 



The synthesis of proteins can be regarded as the growth of proto- 

 plasm, a mixed crystal. Foreign proteins or various amino acids are 

 adsorbed to the surface of the crystal or the protoplasm, and after 

 the establishment of the rearrangement of amino acids or of polar 

 groups in the protein molecules to answer the template pattern of the 

 protoplasm, they may be incorporated into the crystal. Such must be 

 the synthesis of proteins, whereby the growth of the protoplasm is 

 achieved. 



It has been already stated in Part II, Chapter VIII, that nucleic 

 acids possess the faculty to strengthen the pattern of the protoplasm. 

 Haurowitz (26) claimed that the role of the nucleic acids is apparently 

 to maintain the template protein film in the expanded state, a state 

 in which proteins do not remain unless exposed to the stress of inter- 

 face forces. In addition to such an expanding action, if any, nucleic 

 acids may have the hardening action by which the structure of the 

 polymerization product of proteins is made firm. 



Thus, the writer has come to possess the opinion that the role of 



