RESPIRATION AND OXIDATIVE PHOSPHORYLATION 103 



1 I ' ' ' ' I 



450 500 



Wavelength (mp) 



Fig. 1. Difference spectra of bull spermatozoa at 25°C. Cells washed 

 and suspended in RP, pH 7.2, 8.9 X 10 8 cells/ml. Sample H477. Solid 

 line: (anaerobic, lactate 20 mM) - (aerobic, endogenous substrates). 

 Dashed line: (anaerobic, lactate, CO) — (anaerobic, lactate). Dotted line: 

 (anaerobic, lactate, CO, dithionite) — (anaerobic, lactate, CO). 



Before this point is reached, a partial reduction corresponding to 

 the aerobic steady state of lactic acid metabolism can be recorded, as 

 will be seen later. Also shown (Fig. 1) is the formation of a cyto- 

 chrome a 3 -carbon monoxide complex with absorption bands at 585 

 and 425 m^. The disappearance of the cytochrome a 3 absorption 

 which follows the treatment by CO (trough at 445 nut) and compari- 

 son between this trough and the previous Soret band at the same 

 wavelength indicate a one to one ratio of cytochrome a 3 to cyto- 

 chrome a. The effect of dithionite on anaerobically reduced samples 

 shows the presence of a chemically reducible component of the cyto- 

 chrome b type, called b(d). 



On a number of spectra, obtained at room temperature with vari- 

 ous differential arrangements, absorption bands have been located 

 at the following wavelengths: at 605 and 445 m/i absorption bands 

 corresponding to reduced cytochromes a and a 3 , and at 552 m/x and 

 415 m/x, bands indicative of cytochrome c. The 552 m/x absorption is 

 in fact due to the mixture of cytochromes c and c 1 . After one-hour 

 extraction by distilled water, which removes cytochrome c, cyto- 



