37. NUCLEIC ACID AND PROTEIN SYNTHESIS 397 



dertakes synthesis of a new protein (adaptive enzyme formation). Thus 

 far, however, it has been found difficult to obtain active cell-free prepara- 

 tions which can be dissected as extensively as has been possible with the 

 mammalian systems. The experimental problem is complicated further by 

 the danger of contamination of "subcellular" fractions by whole bacteria. 

 This danger is potentiated by the fact that thus far, the most active protein 

 synthesizing preparations from bacteria have been associated with cell 

 membranes which sediment at forces close to those which sediment whole 

 bacterial cells. Nor is it enough to reduce whole-cell contamination of frac- 

 tions to numbers which by themselves will give negligible synthesis, for 

 whole cells may function more efficiently in the presence of the particular 

 cell fraction one is examining by virtue of being exposed to an ideal culture 

 medium. 210 



Earlier studies, notably by Gale and Folkes, and by Spiegelman (cf. 

 review by Spiegelman 4 ) showed that various sonically disrupted or osmot- 

 ically lysed preparations of bacterial cells or protoplasts were capable of 

 protein synthesis, and that removal of a large part of the RNA of the prep- 

 arations by ribonuclease led to a cessation of this synthesis. The activity 

 could be restored by RNA or, where RNA synthesis was possible, by ap- 

 propriate RNA precursors. Similar relationships were shown for DNA vis- 

 a-vis protein synthesis by these workers. The extent to which these results 

 were influenced by whole cells in the preparation is not clear. 



Gale 21 has obtained evidence that in sonically disrupted staphylococcal 

 preparations under conditions where protein synthesis is inhibited by 

 chloramphenicol, or by withholding other amino acids essential for protein 

 synthesis, C 14 -amino acids accumulate on a material tentatively identified 

 as polynucleotide in nature. Release of the inhibition results in the disap- 

 pearance of the amino acids from this fraction and their appearance in pro- 

 tein. This result resembles that of Gros, quoted above, in whole E. coli 

 cells, and fits agreeably with the general picture of protein synthesis in 

 mammalian systems developed in the earlier sections of this chapter. 



Attempts by several workers to fractionate various disrupted bacterial 

 cell preparations 100 ' 188 ' 189, 211 " 213 have led to one tentative generalization: 

 that unequivocal protein synthesis (requiring all amino acids and resulting 

 in enzyme increase as opposed to simple amino acid incorporation) seems 

 to be more closely associated with the fragmented cell membrane material 

 than with the ribosomes or other less easily sedimentable fractions of the 

 cell. 



210 P. Rogers and G. D. Novelli, Federation Proc. 18, 1232 (1959). 



211 B. Nisman, Biochim. et Biophys. Acta 32, 18 (1959). 



212 P. Brookes, A. R. Crathorn, and G. D. Hunter, Biochem. J. 71, 31P (1959). 



213 G. E. Connell, P. Lengyel, and R. C. Warner, Biochim. et Biophys. Acta 31, 391 

 (1959). 



