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W. W. Wainio 



that Warburg (1949) has not found a carbon monoxide compound of any 

 metal other than iron which is decomposed by light. For example, the 

 carbon monoxide compound of the copper of haemocyanin which has a 

 Cu:CO ratio of 2:1 (Kubowitz, 1938) is not sensitive to light. 



*.zoo 



*.I00 





 '.100 



400 



650 



450 500 550 600 



Vlave Lenqih (m/i) 



Fig. 2. Effect of nitric oxide on the spectrum of reduced cytochrome c oxidase. 



Based on a study of the equilibrium between cytochrome c oxidase and 

 carbon monoxide, Wald and Allen (1957) have concluded that the enzyme 

 must contain more than one haem/molecule. They found the curve relating 

 per cent saturation of the enzyme with carbon monoxide to the partial 

 pressure of carbon monoxide to be shghtly inflected and concluded that this 

 was evidence for the interaction of haems. If it is assumed that carbon 

 monoxide combines with the copper and that there are two copper atoms per 

 molecule, the results of Wald and Allen would be explained. 



