ROHERT L. SEARLS AND I). R. SANADI 



161 



Ac is the absorbancy of the complex (C) and K is the dissociation 

 constant. 



FMN 

 1 



+ T(SH)2 ;: 

 (T(SH)2) A^ 



(FMN) 



C 

 - K 



{4) 



{5) 



Fig. 4 shows the dependence of the absorbancy of the 535 n\^ peak, 

 obtained within 5 minutes after mixing, upon the concentration of 

 FMN in the mixture (which is varied from 5xlO~^^tolSXlO~'' 

 M) at a fixed concentration (1.8 X lO-^ M) of reduced thioctate. 

 The relationship, as plotted, is linear and meets the criterion expected 

 for a complex. 



Electron spin resonance (ESR) measurements, carried out in the 

 laboratory of Dr. B. Chance, showed no signal immediately after 

 mixing equal volumes of dihydrothioctate (2.4 X 1^^~" ^) ^^^ FMN 



O 

 O 



X 



-l< 



-xlOO 



Fig 4. Effect of reactant concentration on the FMN-T(SH)2 complex. A is the 

 height of the peaks ofjtained 5 minutes after mixing; S is the FMN concentration; 

 the T (SH)2 concentration was 1.8 X 1^" ^^ 



