Energy Transfer and Conservation in the Respiratory Chain 



605 



4 mM 

 Succinote 



550-540m>j± 

 log lo/ 1 =0.010 

 T 

 , 2DiM 

 Fe/sec 



4mM 

 Succinate 



1 500-465 m>i± 



' log U/I =0,010 



T 



flavin /sec 



l3i5fold 

 lluli 

 B 



-50 sec- 



4 mM 

 Succinate 



1 300-275 mp A 

 log Io/I = 0005 



> O.I5;jM ^ 

 U-Q/sec 



\- 



63 fold ^-.^ 



dilution. 



C D 



Fig. 2. The kinetics of the reduction of the cytochrome, flavin and ubiquinoue 

 components of a Keilin and Hartree heart-muscle preparation at 12°C. In 

 records A, B and C the dilution is 13-5-fold; in record D the dilution is increased 

 to 63-fold. The aerobic heart-muscle preparation is pretreated with 1-2 mM 

 cyanide and the moment of addition of 4 mM succinate is indicated by the arrow. 

 The rates of reduction of the components, measured as soon as the mixing artifact 

 has subsided, are given in iron atoms (1 equivalent), flavm or ubiquinone (2 equiva- 

 lents) per sec. A downward deflection of the trace indicates (A) an increase of 

 absorption at 550 m^a; (B) a decrease of absorption at 465 m^t*, (C) an increase 

 of absorption at 562 m/i; and (D) a decrease of absorption at 275 m//. In records 

 A-C, a tungsten lamp was used; in record D a hydrogen lamp was used. The 

 U-Q rate was computed on the basis of A? = 11 cm~^ x mM~*^ (Expt. 989c). 



All rates are given in terms of two electrons per second. Thus the rates of 

 reduction of flavin and ubiquinone are measured directly as in Fig. 2, while 

 those of cytochrome are divided by two. 

 UQ 



0-15-0-25 / \ 



±AM / \ 

 0-26 ' ^ 



succinate ^ fp =^ 



0-44 



a, ^ Oo 



(5) 



