THE FLAVOPROTEINS 



141 



The equations representing the dissociation and the equiUbrium 

 expression or dissociation constant for the formation of the complex 

 are as follows: 



( 3 ) Complex = CR + TPNHj 



_ (CR) (TPNH=) 

 ( Complex ) 



The velocity of the reaction is proportional to the concentration 

 of the complex. 



( 5 ) v = Kr i Complex ) 



Since ( 6 ) ( CR ) totai = ( CR ) + ( Complex ) 



Kr(TPNH2)(CR) total 



(7) V = — ^^ 



Ki+ (TPNHO 



This equation is essentially the Michaelis-Menten equation. I am 

 considering it in some detail only because I wish to use it in refer- 

 ence to the determination and definition of enzyme activity. 



In the above derivation I have assumed that the products of the 

 reaction have no inhibitory influence, or that the conditions are such 

 that the concentrations of the products are negligibly small. The 

 velocity plotted against the concentration of dihydrotriphosphopyr- 

 idine nucleotide is given in Figure 3. This curve is strictly in accord 

 with equation 7. 



2.0 X 10 



FIGURE 3 



