HUGO THEORELL 



TABLE I 

 Dissociation of O.Y.E. by Different Anions (0.1 M) at pH 4.40, 23.5° C. 



Salt 



ko X lO'' 



sec. 



Na formate 



Na acetate 



NaF 



NaH2P04 



Na2S04 



NaCl 



NaNO, 



NaBr 















1 



9 



33 



63 



99 



When anions of strong acids are present, the value of k-z is 

 greatly influenced by the hydrogen ion concentration (see 

 Figure 2). In the acid range ko was found to be proportional 

 both to [H+] and (Q-). 



Fig. 2. The value of kz for 

 O.Y.E. as a function of pU in 0.4 M 

 NaCl (from ref. 24). 



k.'IO 



4 pH 5 



Fig. 3. The value of ^'i for 

 FMN + apoprotein as a function of 

 pU. • • • in 0.1 M acetate buffer. 

 OOO in 0.1 M glycine buffer. The 

 lower curve (experimental points 

 omitted) is ki for riboflavin + apopro- 

 tein at 13.5 °C. (from ref. 24). 



The first splitting of the O.Y.E., in 1934 (17), was accom- 

 plished by dialysis against weak hydrochloric acid. As we 

 can see now, this was a fortunate choice, since the velocity of 

 splitting is proportional to the square of the concentration of 



286 



