BIOLOGICAL ROLE OF PENTOSE NUCLEIC ACIDS 517 



tion with the role played by PNA in protein synthesis, Bounce and Kay^^^ 

 have published the very interesting, but as yet preliminary, report that 

 PNA can be phosphorylated by the ATP-myokinase system. 



However, the most important — and to the author of this review the most 

 gratifying — discoveries in the field of the biological activities of PNA come 

 from a series of recent papers which report that ribonuclease has been used 

 as an analytical tool for biochemical experiments. The most complete and 

 interesting results so far reported are undoubtedly those of Gale and 

 Folkes.^*^'^*^ Working on disintegrated Staphylococci which no longer re- 

 spire, nor multiply, they found that these "cells" can still incorporate 

 amino acids into their proteins, provided ATP and hexosediphosphate are 

 present in the medium. Removal of the nucleic acids by nucleases or NaCl 

 treatment strongly reduces this incorporation; addition of the nucleic 

 acids fraction restores to a large extent the capacity to incorporate several 

 of the amino acids into the proteins. Going a step further. Gale and Folkes^*^ 

 studied the effects of removal and addition of the nucleic acids on the actual 

 synthesis of several enzymes including catalase and the adaptive synthesis 

 of /S-galactosidase. Here, again definite results were obtained in the case of 

 the disrupted cells, the nucleic acids of which had been removed. Addition 

 of bacterial PNA was most active in enhancing the synthesis of catalase 

 while DNA, especially if isolated from adapted cells, proved to be the best 

 for the stimulation of the synthesis of the adaptive |S-galactosidase. Gale 

 and Folkes^^' conclude, somewhat along the line of Caspersson's ideas, that 

 DNA acts as an organizer for the synthesis of specific PNA's, which some- 

 how catalyze protein synthesis. 



Similar but less complete results have also been reported by Lester,^^^ 

 who found that Micrococcus lysodeikticus when lysed with lysozyme in the 

 presence of sucrose, is still able to incorporate labeled amino acids into its 

 proteins. Here again, ribonuclease exerts a powerful inhibitory effect on 

 the phenomenon. Deoxyribonuclease, on the contrary, stimulates the in- 

 corporation. 



It has been amply demonstrated, especially by Borsook and his school, 

 that the incorporation of amino acids into proteins is an energy requiring 

 process; the possibility is thus open that, in the experiments of Lester,'®'* 

 ribonuclease somehow inhibits the oxidative mechanisms of the cell. A re- 

 cent investigation by Beljanski^®^ in this laboratory has ruled out this possi- 

 ble objection by showing that ribonuclease has no effect on the respiration 

 of lysed Micrococcus lysodeikticus cells. Similarly, it has been reported re- 



2" A. L. Bounce and E. R. M. Kay, Proc. Soc. Exptl. Biol. Med. 83, 321 (1953). 

 "2 E. F. Gale and J. P. Folkes, Nature 173, 1223 (1954). 

 -" E. F. Gale and J. P. Folkes, Nature 173, 1223 (1954). 

 2" R. L. Lester, J. A7n. Chem. Soc. 75, 5448 (1953). 

 2"M. Beljanski, Biochim. et Biophys. Acta 15, 425 (1954). 



