IRREVERSIBLE MONOLINEAR CHAINS 337 



Activity-time curves are plotted for various additions of enzyme or ascor- 

 bate and the transitions from one steady state to another are easily de- 

 monstrated. It was possible by changing the areas of the membranes to 

 show that the attainment of a steady state depends on the diffusion capac- 

 ity of the system relative to the enzymic activity. 



Extension to Longer Monolinear Chains 



The kinetics developed above can be easily extended to chains of any 

 length: 



B^C 



and it will suffice to enumerate the laws governing such systems. 



(1) The rate of formation of product from an enzyme chain of any length 

 in a steady state is determined by the rate of the first reaction; when a 

 steady state does not occur, the rate is determined by that reaction with 

 the lowest maximal rate. 



(2) The concentration of any intermediate will depend on the rate con- 

 stant, Michaelis constant, and concentration of the enzyme acting upon it; 

 for the intermediate J it is given by 



(J) ^ M^IA^ (7-12) 



' (A)(F, - F,) + V,K, ^ ' 



The relative concentrations may be visualized on v-(S) curves, as shown 

 for a four-enzyme system in Fig. 7-5 (VII-VIII). 



(3) The noncompetitive inhibition of any enzyme after the first, when 

 the system is initially in a steady state, will have no effect on the formation 

 of product until the inhibition has reduced the maximal rate of that enzyme 

 to a level lower than the initial uninhibited rate (see Fig. 7-5, VIII). 



(4) When a system is in a steady state, competitive inhibition of any 

 enzyme after the first will have no effect on the formation of product, 

 unless the intermediate which is the substrate for that enzyme cannot 

 increase in concentration sufficiently to antagonize the inhibition and 

 maintain the rate. The effect on product formation will thus depend on 

 the spatial organization or physical state of the system. 



