Cell Structure and Metabolic Regulation 43 



into the medium and, we think, begins to be attacked there by 

 the RNAase which is simultaneously released from the 

 particles. So now it would seem that the addition of ATP or 

 pyrophosphate, or at higher concentrations AMP or phos- 

 phate, complexes the Mg2+ which binds the RNA to the 

 protein of the particles. The enzymes are released from their 

 possible site of synthesis by a process which includes the dis- 

 ruption of the synthesizing structure. 



Does this happen in vivot Is this the way these presumably 

 newly-synthesized enzymes are released from their site of 

 synthesis to their eventual destination, in this case the 

 zymogen granules via the ER? Can we generalize and say 

 that macro structures can be built or destroyed by such 

 complexings which involve smaller molecules? DNP has an 

 effect on this one particular complexing (Table VII); can 

 other phenolic compounds have similar effect; can thyroxine? 

 It is no startling revelation to proclaim that chemical mechan- 

 isms modify structural form; but we have now reached the 

 brink where we can ask experimentally meaningful questions. 

 Unlike a certain well-known statesman, let us not totter on 

 this brink, for it is not one which borders on complete destruc- 

 tion; let us jump in, for the heady seas of the relationships of 

 structure and function await us. 



Acknowledgement 



The author gratefully acknowledges the advice of Drs. K. R. Porter 

 and G. E. Palade on some aspects of this paper. 



REFERENCES 



Bennett, H. S. (1956). J. biophys. biochem. Cytol., 2, suppL, 99. 

 Bernhard, W., and Rouiller, C. (1956). J. biophys. biochem. Cytol., 



2, 73. 

 Cahill, G. F., Hastings, A. B., Ashm^re, J., and Zottu, S. (1958). 



J. biol. Chem., 230, 125. 

 Chapman-Andressen, C, and Holter, H. (1955). Exp. Cell Res., 



suppl. 3, 52. 

 Conway, E. J. (1951). Science, 113, 270. 

 CoRi, C. F. (1955). In Enzymes: Units of Biological Structure and 



Function, p. 573. Ed. Gaebler, O. H. New York: Academic Press. 

 CowGiLL, R. W., and Cori, C. F. (1955). J. biol. Chem., 216, 133. 



