106 



4101 ■ '| » ' l ' I '' 1^50 



PIERRE H. GONSE 



5101 i'| l'| I | i 1 ! 1 ' 1 ! 1 ' I ' I ' I ' I * ' I 610 m H 



Fig. 4. Difference spectra at liquid nitrogen temperature in the pres- 

 ence of 50% glycerol. Samples H476 and M5. (Dithionite) - (aerobic, 

 endogenous substrates). Upper curves: bull spermatozoa, washed and 

 suspended in RP, pH 7.2. Lower curves: dog spermatozoa, lightly washed 

 and suspended in RP-GG, pH 7.3. 



Following extraction of cytochrome c from bull spermatozoa, the 

 absorption band of cytochrome c 1 stands out clearly at 552 nv at low 

 temperature (Fig. 5). On the same material, difference spectra also 

 recorded at liquid nitrogen temperature indicate dithionite-reduced 

 cytochrome b(d) at 561 nut; in dog sperm after freezing and thawing, 

 a dithionite-reducible material, analogous to mitochrome and distinct 

 from cytochrome b(d), absorbs at 555 ni/x (Fig. 5). The existence of a 

 cytochrome with absorption at 561 m/*, instead of 558 m/x as for cyto- 

 chrome b (at low temperature), is further demonstrated in Fig. 6. In 

 this spectrum of dog spermatozoa, cytochrome b(d) appears at 560.5 

 m/x, distinctly separated from cytochrome b (558 nut), but in this 

 case reduction follows treatment with the respiratory inhibitor, anti- 

 mycin A, instead of dithionite. Cytochrome b(d) is repeatedly found 



