FUNCTION OF FLAVOENZYMES IN ELECTRON TRANSPORT 



TABLE IV 



Properties of Diaphorase Activities of Submitochondrial 

 Fractions Prepared According to Kielley and Kielley (1953) 



F"or experimental details, see Danielson, F>nster and Ljunggren [25]. 



145 



Submitochondrial 

 fraction 



Additions 



Diaphorase activity 



/Ltmoles DCPIP reduced/ 



min./g. liver 



DPNH 



TPNH 



Supernatant none 028 030 



8 mg. Tween 0-70 071 



8 mg. Tween + lo^** M dicoumarol 005 0-04 



Pellet (light) none 050 o-oo8 



8 mg. Tween 050 0-038 



8 mg. Tween + lo"" M dicoumarol 0-46 o-oo6 



The light sediment exhibited a DPXH oxidase activity, as shown in 

 Table V. This was sensitive to amvtal and antimvcin A. When cytochrome 

 c was added, the respiration was increased, and the stimulated respiration 

 was only partially inhibited by these agents. Thus this pellet seems to 



7 6 5 4 

 -log M dicoumarol 

 Fig. 3. Effect of dicoumarol on diaphorase activities of submitochondrial 

 fractions prepared according to Kielley and Kielley (1953). Activities measured bv 

 using DPNH as substrate and DCPIP as hydrogen acceptor. For experimental 

 details, see Danielson, Ernster, and Ljunggren [25]. 



contain both the "internal" type of DPXH oxidase of mitochondria, and 

 the "external" type of DPXH cytochrome c reductase (cf. [26, 27]). As 

 Professor Lindberg reported earlier in this session [28], the two systems 

 may also be distinguished by their different degrees of sensitixitv to desa- 

 minothyroxine. 



Using the "internal" DPXH oxidase system, that is, the light pellet 

 without supplementation with cytochrome r, it was found that the amytal- 

 block now could not be by-passed by added \ itamin K3 (Fig. 4). However, 



VOL. II. — L 



