376 



R. W. Henderson and W. A. Rawlinson 



fractions (Fig. 2) and the O2 uptake determined (Fig. 4). Great avidity for 

 copper was shown; combination, however, was in the ratio of 2 g atom 

 of Cu/mole globin. 



^ 150 



- 0-5 1-0 1-5 2-0 2-5 3-0 3-5 



moles xlO^giobin/flosK 



Fig. 4. Inhibition by globin (from horse-heart myoglobin) of the copper- 

 catalysed oxidation of ascorbate. (Experimental conditions: Warburg mano- 

 meters; 007 M sodium phosphate buffer, pH7-3; 0-02 m sodium ascorbate, 

 and 1 fig of copper/flask at 37°C.) 



Eq of Cytochrome c in the Presence of Copper 



Low-iron content samples in general show a slightly higher Eq (about 

 15 mV) than the higher-iron content samples (Henderson and Rawlinson, 

 1956a). This was attributed, however, to the presence of modified cytochrome 

 c. We have now examined the Eq of a '0-34% Fe' content sample of M. 

 heart c before and after addition of copper in shght excess of its binding 

 capacity and find the value to remain unaltered (£"0 = + 0"26 V, « = 1). 

 The sample containing copper showed a somewhat increased rate of autoxi- 

 dation. This electrometric result is compatible with an aggregation where 

 there is no significant interaction one with another between the groups 

 oxidized/reduced (Shack and Clark, 1947), although of course it neither 

 proves nor disproves a state of aggregation. 



Crystallization of Cytochrome cfrom a 'Low-iron'' Content Preparation 



Since the first crystallization of cytochrome c from King penguin muscle 

 by Bodo (1955) there have been several reports, notably from the school of 

 Okunuki, of crystallization of the pigment from a number of different 

 tissues (see Morton, 1958). Much work has been carried out on cytochrome 

 (■ from mammalian heart muscle, especially from ox-heart. To the best of 

 our knowledge cytochrome c from this source had been crystallized only after 

 resin-column treatment. 



