Cytochrome Oxidase Components 341 



cytochrome c could be extracted from the mitochondria in the anaerobic 

 state than that in the aerobic state. 



This is not simply a function of the state of oxidation of the cytochrome 

 c. After acetone powders were obtained from aerobic and anaerobic mito- 

 chondria, they were treated in order to oxidize the cytochrome c. The 

 difference in the total amount of cytochrome c extractable from the two types 

 of mitochondrial powders remains the same even when all the cytochrome is 

 oxidized prior to extraction. This difference in extractability, then, can be 

 interpreted as due to the difficult extraction of the cytochrome-coupler 

 compound and not simply due to a difference in the extractability of free 

 oxidized and reduced cytochrome c. 



When aged mitochondria in which oxidation and phosphorylation are 

 uncoupled were employed, the state of oxidation still affected the amount of 

 cytochrome c which could be extracted. Thus, in agreement with other 

 studies (Remmert and Lehninger, 1959), it would appear that the carrier 

 inhibitor compound is still functioning even after ageing, though the steps 

 involved in the transfer of the high energy bond are disrupted. 



In addition to the previous evidence for the existence of cytochrome c 

 inhibitor complex, our studies (Crawford and Morrison, 1959) on the 

 succinate-cytochrome c reductase system have also yielded evidence that a 

 cytochrome ^-inhibitor complex may exist. A study of the rate of reduction 

 of cytochrome c with our succinate-cytochrome c reductase preparation has 

 indicated the presence of an inhibitor in the preparation. On extraction of 

 this preparation with /50-octane, the kinetics can be interpreted as an increase 

 in inhibitor. A study of the kinetics after the addition of tocopherol or 

 vitamin K^ indicates that these lipids are able to reverse the effect of the 

 inhibitor. 



These results are compatible with a scheme in which the cytochrome first 

 reacts with an inhibitor and the cytochrome-inhibitor compound can no 

 longer be alternately reduced and oxidized. 



Z?++ + / + Ci+++ -^ b+++ ~ / + Cj++ 



Following this, the effect of the lipid may be to react with the carrier ~/ 

 compound to form a complex of the type I ^^ Xin which Zis the lipid factor. 

 This compound in turn might react with inorganic phosphate (/*,) to form 

 complexes of the X ^^ P type, and preliminary evidence of such lipid- 

 phosphate intermediates has already been obtained (Conover and Witter, 

 1958; Boyer, Dempsey, Schulz and Andesegy, 1959). 



^+++ r^i ^ x-^Ir^ X + b+++ 



I'^ X + Pi-^I + X ^P 



Spectrophotometric results are perfectly compatible with these results. 

 On addition of succinate, both the cytochromes b and c^ are reduced. After 



