REGENERATIVE SYSTEMS 



359 



(AX) and decreases with rise in (C). It would not be so easy to predict 

 that the ratio would slowly fall with increasing (B)^. Such changes may 

 be of importance in experiments where (B) or (BX) is determined during 

 the steady state, as in the spectrophotometric measurement of DPNH 

 in oxidation-reduction sequences. 



(cycl e) 



i(E2) 



Fig. 7-25. Noncompetitive inhibition of Eg in the cyclic system shown 



in Fig. 7-16. The variation of the over-all cycle inhibition with the 



individual inhibition is shown. Curve 1: (M); = 0.1 vaM; curve 2: 



(M), = 1 mi¥; curve 3: (M)^ = 10 mM. 



Conditions for the Steady-State and Maximal Rates 



A regenerative system can always assume a steady state whatever the 

 concentrations of substrate, regenerant, or final acceptor. This is because 

 the ratio (BX)/(B), will adjust in any case to a value so that v^ = t'a- This 

 can be shown rigorously in the following manner. An expression for (B) is 

 derived from Eq. 7-40 and for (BX) from Eq. 7-41; the addition of these 

 will give (B);; the rates i\ and V2 for a steady state are equal and repre- 

 sented by v^f, the equation for (B), is solved for v^^. 



