The Cytochromes of Plant Tissues 



489 



Reduction of the corn pollen homogcnate in the presence of HOQNO also 

 produces a remarkable spectrum. Under such conditions in the Keilin and 

 Hartree muscle preparations or in yeast suspensions, only cytochrome b 



Anfimycin A / OPNH 



Fig. 7. Difference spectra (at — IWC) 

 obtained from etiolated mung bean hy- 

 pocotyls. Tlie spectra represent the dif- 

 ference in absorption between oxidized 

 mitochondrial suspensions and suspen- 

 sions treated as indicated in each curve. 



Fig. 8. Difference spectra (at — 190°C) ob- 

 tained from cabbage mitochondria. The 

 spectra represent the difference in absorption 

 between oxidized mitochondrial suspensions 

 and suspensions treated as indicated on each 

 curve. 



(at 560 m/Li) remains reduced while the (a + ^3) and c components become 

 more oxidized. In the com pollen homogenate three well defined peaks 

 appear in the presence of HOQNO, these peaks have their maxima at 555, 

 558 and 564 m/n. Other illustrations of this behaviour toward HOQNO or 

 antimycin A, will be given below. All plant tissues that have been examined 

 so far characteristically show these same three absorption peaks following 

 treatment with HOQNO or antimycin A. 



K 



