RESPIRATION AND OXIDATIVE PHOSPHORYLATION 



105 



■ '■ ," ■ ■ ■'■ 



1450 m^j 



t 

 AQD. 

 0.01 cm"' 



A O.D. 

 0.005 cm" 1 

 i 



Fig. 3. Difference spectra of Spisula spermatozoa at liquid nitrogen 

 temperature. Cells in SW-GG. Sample S10. Solid line: (anaerobic, KCN 8 

 mM) — (aerobic, endogenous substrates). Dashed line: (anaerobic, KCN, 

 dithionite) — (anaerobic, KCN). 



chrome c is evidenced by absorption bands at 550 m^ and 4 1 7 ra.fi. A 

 cytochrome Mike component absorbs at 562 and 430 my*. But at low 

 temperature, spectrophotometric records indicate that this (b) com- 

 ponent is actually double with alpha absorption bands at 557 and 

 562 ni/x (Fig. 3). If a shift of 3 m/x toward shorter wavelength is as- 

 sumed upon cooling, these pigments, at 25 °C, should absorb at 560 

 and 565 m/x; however, what is actually found is a fused absorption at 

 562 m/x, here attributed to cytochrome (b). 



Among other features of Fig. 3, there is a noticeable shift of the 

 alpha absorption of cytochrome a in the presence of KCN, which, as 

 well as azide, under aerobic conditions brings about reduction of 

 terminal cytochromes. With addition of dithionite in an anaerobic 

 sample, absorption bands appear at 556 and 427 ni/x and indicate 

 further reduction of a (b) component, possibly the lower of the (b) 

 cytochromes previously defined. 



As noted for Spisula sperm low-temperature spectroscopy permits 

 separation of nearby absorption bands. In dog or bull spermatozoa 

 (Fig. 4) one can distinguish in this way, "without separate specific 

 treatments, cytochromes a 3 , a, c, c 1 , b, and b{d) by their absorbencies 

 at 444, 601, 548, 553, 558, and 561 m/x, respectively. Cytochrome b(d) 

 is particularly noticeable at low temperature by its beta absorption 

 at 535 itu/.. Attention is directed to the similarity between spectra ob- 

 tained on dog and bull spermatozoa. 



