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7. INHIBITION IN MULTIENZYME SYSTEMS 



levels to overcome the inhibition on Eo. However, in actual systems, there 

 will be a limit imposed on the level to which (B), can rise. It is important 

 to emphasize that competitive inhibition of any enzyme after the first 

 in an irreversible monolinear chain will alter the rate of formation of the 

 product by a degree primarily dependent on the physical state of the sys- 

 tem, and particularly on the presence and nature of compartmentalization 

 of the reactions in the system. 



Fig. 7-9. Comparison of noncompetitive and competitive inhibi- 

 tions of Eo in a monolinear chain. A'j = 10 mJ/, iv^j — 2 m3I, 

 and (A) = 1 in3I. Curve 1: Fj/Fg = 10. noncompetitive; curve 2: 

 Fi/F2 = 10, competitive; curve 3: VJV2 = 1, noncompetitive; 

 curve 4: V-^/V2 = 1; competitive. 



(C) Reaction of the inhibitor with the intermediate B. A substance that 

 reacts with B according to the equilibrium expression I + B ;^ IB will 

 reduce the concentration of free B and hence the rate of reaction 2. Since 

 there is no effect on reaction 1, B will be formed more rajudly than it is 

 transformed into C. Whether the rate of reaction 2 will recover towards 

 the initial level will depend on the equilibrium constant K ,^ and the amount 

 of I relative to B. If (I) is large, (B) may be kept close to the equilibrium 

 value and the formation of C may be depressed to a level that is stable, 



