Cytochrome Oxidases of Pseudomonas Aeruginosa 



307 



protein crystallized are shown in Table 2. The absorption spectrum of the 

 protein is as shown in Fig. 2. Finely crystallized P-blue protein has a shape 

 as shown in Fig. 3. The copper bound on the protein can be spht off from the 



Table 2. General properties of P-cytochrome oxidase, crystalline 

 p-cytochrome-551 and p-blue protein 



protein by dialysing it against cyanide solution at a neutral pH range. The 

 copper-free P-blue protein does not show any absorption peak in the visible 

 wavelengths even in the presence of oxidizing reagents, and the same absorp- 

 tion peak around 630 m/« appears immediately after addition of a small 

 amount of CUSO4 the colour of which can hardly be estimated spectro- 

 photometrically. 



Reaction of Ox-heart Cytochrome a and Pseudomonas Cytochrome Oxidase 

 with their Related Respiratory Components 



The hydroquinone oxidation by purified cytochrome a increases in rate 

 up to its upper limit with an increasing concentration of cytochrome c 

 externally added. Just at the concentration of cytochrome c at which the 

 cytochrome oxidase activity reaches its maximal rate, the molar ratio of 

 cytochrome c to cytochrome a is approximately one. This value is indepen- 

 dent of the reactivation of the cytochrome oxidase activity of the cytochrome 

 a preparation by the use of the non-ionic detergents as described above. The 

 K^ for cytochrome c is 3 x 10~^ m, which is similar to that obtained by 

 Slater (1949). Purified cytochrome c^ is only slowly oxidized by cytochrome a, 

 and the rapid oxidation of cytochrome c by the cytochrome a preparation is 

 not influenced by the addition of cytochrome q. On the other hand, the slow 

 oxidation of cytochrome q by the cytochrome a preparation is notably 

 accelerated by the addition of a small amount of cytochrome c, as shown in 

 Fig. 4. 



P-cytochrome oxidase rapidly oxidizes the reduced P-cytochrome-551, and 

 the reduced P-blue protein, but not the reduced P-cytochrome-554. The 

 typical cytochrome c's crystallized from baker's yeast and animal sources are 

 very slowly oxidized by the oxidase, while the cytochrome a preparation does 

 not oxidize P-cytochrome-551 and P-blue protein. P-cytochrome oxidase 

 can oxidize several reductants such as hydroquinone, /j-phenylenediamine, 

 ascorbate, etc., as shown in Table 3 (Horio, 1958b). The oxidations by 



