COMPOSITION OF CYTOCHROME c OXIDASE 



By W. W. Wainio 



Bureau of Biological Research and Department of Physiology and Biochemistry, 

 Rutgers, The State University, New Brunswick, N.J. 



INTRODUCTION 

 When Keilin and Hartree (1938a, 1939) proposed that cytochrome a con- 

 sisted of two components, namely, cytochrome a and cytochrome a^, they 

 introduced a concept that has occupied many of the investigators in this field. 

 In Keilin and Hartree's experiments both carbon monoxide and cyanide 

 caused alterations in the 605 mjti band of reduced cytochrome a, viz. a 

 spreading to 590 mjii. The 448 m/n band disappeared and was replaced by an 

 intensified absorption at 430 m/u when carbon monoxide was used and by a 

 new absorption at 452 m/.i when cyanide was added. It was concluded by 

 them that the component with a strong affinity for carbon monoxide in the 

 reduced state and for cyanide in the oxidized state, and with a weak absorp- 

 tion at 600 m^ (relative to 605 m/u) and a strong absorption at 448 mfi 

 (relative to 452 m/i) was cytochrome a^. The somewhat anomalous component 

 with a strong absorption at 605 m/j, and a weak absorption at 452 m/t was 

 cytochrome a. Cytochrome a^ was tentatively identified with cytochrome 

 oxidase, and the possibility that cytochrome oxidase is a copper-protein was 

 considered in some detail. 



There was an immediate objection by Stern (1940), who stated that 'If 

 the relationship is actually that described and sketched by the authors [i.e., that 

 the a- and y-bands of cytochrome ^3 are weak and strong, respectively, com- 

 pared with those of cytochrome a], it can hardly be reconciled with the 

 further statement that the a and a^ components are both haem-protein 

 complexes with an identical haem nucleus and that both occur in comparable 

 concentrations in various oxidase preparations'. 



Stotz (1942) and Lundegardh (1953) raised lesser objections, but since 

 further work from their laboratories has emphasized the separateness of the 

 two enzymes, it may be concluded that these objections are no longer 

 considered valid. 



We became interested in this problem in 1948 after having successfully 

 prepared a soluble cytochrome oxidase with deoxycholate (Wainio, Cooper- 

 stein, KoUen and Eichel, 1947, 1948). Our view at that time was that cyto- 

 chrome oxidase was a copper-porphyrin-protein and that the anomalous 

 behaviour of the enzyme in the presence of carbon monoxide and cyanide 



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