THE SYNTHESIS OF PROTEINS 5 



reaction A^ B but not the other reactions. Addition of this catalyst 

 will result in a rapid formation of B, until [^] = [-S] with the result 

 that a large amount of B and very little C, D, or E is formed. The re- 

 action is not at equilibrium and if allowed to proceed by itself will end 

 at the same state as though the catalyst had not been added. In the mean- 

 time, however, large amounts of B have been formed due to the catalyst 

 and could be removed. Similarly, if the concentration of B is greater 

 than that of ^ at the beginning, addition of the same catalyst will now 

 cause A to be formed until [^] = [5] and very little C, D, or E will be 

 formed. The reaction does not take place in the direction B —> A simply 

 because of the addition of the catalyst but because the energy changes 

 require the reaction to go in this direction, and the catalyst merely ac- 

 celerates the rate. In this case, also, the high concentration of A is only 

 temporary, since if left to itself the same final equilibrium conditions, 

 A=B=C=D=E, will be reached. 



The condition may be roughly exemplified by the arrangement shown 

 in Fig. I . The five tubes are connected at the top by open tubing and at 

 the bottom are all connected to tube A by means of tubes which can be 

 closed. If tube A is now filled with water to position i, the water will 



! / 



4. 





BCD 



Figure i. Enzyme reaction model. 



distribute itself until it is at the same level in all tubes, since this is the 

 equilibrium condition. If the connecting tubes at the bottom are closed 

 at the beginning the water will distribute itself slowly through the vapor 

 phase. This corresponds to the "spontaneous" reaction rate. If all the 

 bottom tubes are opened the same final condition will be reached much 

 more rapidly. This corresponds to what will happen if a catalyst is added 



