PROTEINS AND NUCLEIC ACIDS IN SOLUTION 51 



intracellular interphases in which a destruction of but one or two mole- 

 cules can directly change the permeability of the layer, are more likely. 



It is w^ell known that the proto])lasm is characterized by a consider- 

 able heterogeneity and multiphase nature of its iimer structure. At the 

 interphases of media of different composition thin molecular layers 

 necessarily arise which are oriented at the interphase and contribute to 

 the spatial organization of metabolic reactions. 



The presence in the protoplasm of some inner interphases (ergasto- 

 plasmic membranes) forming in the protoplasm a number of internal 

 zones or areas which sometimes sharply differ in pH or redox-potential 

 values may be of great imj)ortance for the sequence of metabolic 

 reactions. In this case damage to only some molecules in the bimolecular 

 interphase switch on a chemical potential difference of much larger 

 volumes or of relatively considerable numbers of components of border- 

 ing media, similar, for example to the situation in which a small hole in 

 a dam can lead to the ultimate levelling of the very large water masses 

 on both sides of it. The role of the change in the permeability of mem- 

 branes has already been stressed by Bacq and Alexander (1956), but 

 these authors meant mainly the membranes of mitochondria, while, in 

 our opinion (Passynsky, 1957b), an essential change in the constants of 

 the transfer in the cell as a whole which is required by the theory of open 

 systems should rather be expected when one takes into consideration 

 the molecular heterogeneity of the structure of the protoplasm. A dis- 

 turbance of the normal sequence of substrate transfer in a number of 

 enzymic conversions with a possible switching off of a number of re- 

 actions at once can be of a more specific or unique character than the 

 damage of one or two enzyme molecules in one of the many hundreds 

 of mitochondrial particles each of which contains hundreds of enzyme 

 molecules. 



The mathematical formulation of the target theory thereby pre- 

 serves its significance both for the case when the primary inactivated 

 volume actually corresponds to the size of molecules, and those cases 

 when it corresponds to the size of a membrane (for example, in the 

 work of Zirkle and Tobias (1956), /• = 800 A, a = 0-26-2-1 A). At the 

 same time a direct relation between the inactivated volume and meta- 

 bolic processes and the physiological state of the cell is evident. 



From the same viewpoint some other fundamental problems of 

 radiobiology can be interpreted (direct and indirect action, analogy 

 with radiomimetic substances, activation of some enzyme systems on 

 irradiation, influence of different kinds of radiation, etc. (Passynsky, 

 1957b) . 



X-ray structural investigation of thin films (300-400 A) of crystalline 



