Enzymic Reactions in Stationary Open Systems 451 



the concentration of the components and to alteration in the diffusion of com- 

 ponents out of the system (brought about, in our experiments, by changing the 

 area of the membrane). In this connection it is noteworthy that, in the establish- 

 ment of a new stationary state, there was first an initial comparatively sharp 

 alteration, after which the concentration returned to a level far closer to the 

 original level, which indicates that open systems have the power of dynamic 

 stabihzation of the stationary state (in the spirit of an extension of Le Chatelier's 

 principle) [5-7]. 



It is interesting to note that this latter power is only retained when the changes 

 in open systems are kept within definite limits. If the chemical reaction is accele- 

 rated too greatly (by the addition of different amounts of enzyme) or if the dif- 

 fusion is increased too much, or if the temperature is raised by more than io°C 

 or lowered by more than 5°C, the abihty of the system to compensate for the 

 change falls off and the transition to stationary states follows curve II in Fig. 6, 

 and, at last, there is a general impairment of the possibility of establishing the 

 stationary state (Fig. 6 curve III). 



From equation (2) one may determine the quantitative limits of changes in the 

 kinetic parameters of the system compatible with its maintainance of the stabil- 

 ized stationary states (of the type of Fig. 6, curve I). 



In equation (2), as we have already stated, 5 is the molarity of the inflowing 

 ascorbic acid solution and a is the molarity of the ascorbic acid solution in the 

 stationary state, calculated from the curves in Figs. 3-5 and 7 (sections AB and 

 DE); from the ratio Sja in equation (2) one can calculate the relative change 

 KJKq before and after introduction of the enzyme. It must be pointed out that 

 the values for K and Kq in the apparatus shown in Fig. 2 differ from those in 

 equation (2) in that Kq denotes the accession of ascorbic acid by inflow and not 

 by diffusion, while K denotes the total loss of ascorbic acid resulting from a 

 chemical reaction of the second order in cylinder A and from diffusion through 

 membrane C; but, in view of the fact that the factors of transfer {Kq and K^ 

 are not influenced by the introduction of the enzyme, the relative change KJKq 

 calculated from equation (2) remains solely dependent on the change in the 

 kinetic parameter i<C resulting from the introduction of the enzyme. Furthermore, 

 the ratio of the stationary levels a/ao, before and after the introduction of the 

 enzyme, was calculated. The results of the calculations from experiments carried 

 out in cylinders I, II, and III are given in Table i. The columns of this table 

 denote : first, the diameter of the membrane of the cylinder; second, the number 

 of the enzyme preparation and the amount used in mg (the original preparation 

 with an activity of 35% on the purpurogallin scale is referred to as I while the 

 same preparation, after having been kept and having a lower activity, is referred 

 to as II); third, the value of S; fourth, the value of (5"/a)o for the initial stationary 

 state in the absence of the enzyme; fifth, the value of A, the relative change in 

 value of KIKq for the initial stationary state and the point of the minimum after 

 the introduction of the enzyme; sixth, the value of a/ao; seventh the character 

 of the stability of the stationary state of the system imder the given experimental 

 conditions (according to whether the curves resemble curve I or curve II in 

 Fig. 6). 



