RESPIRATION AND OXIDATIVE PHOSPHORYLATION 



107 



Fig. 5. Spectra at liquid nitrogen temperature in the presence of 50% 

 glycerol. Samples H434, H437, Ml. (a) Bull spermatozoa, suspended in 

 RP after 4 days extraction by RP at 5°C; absolute spectrum, (b) Bull 

 spermatozoa, washed and suspended in RP, (anaerobic, KCN 1 mM, 

 dithionite) — (anaerobic, KCN 1 mM). (c) Dog spermatozoa, suspended 

 in RP-GG; frozen and thawed, refrozen for recording, both cuvettes 

 treated the same way, one supplemented with dithionite for difference 

 spectrum. 



in spermatozoa of dog and bull and therefore appears to be a normal 

 component rather than an artifact due to cell alteration as is the 

 case after freezing and thawing. The metabolic role of this compo- 

 nent is not as yet clear. It is not reducible by anaerobiosis or by oxi- 

 dizable substrates under aerobic conditions; it is antimycin-sensi- 

 tive. Chance (1958) distinguishes also three (b) cytochromes in 



