Cytochromes Cooled in Liquid Nitrogen 



453 



Fig. 17. The low temperature spectra of 

 the reduced pigments of flight muscle 

 sarcosomes. Curve A represents the 

 spectrum obtained when the pigments are 

 reduced enzymically. The sample cuvette 

 contained a mixture of 0-4 ml of sarco- 

 some preparation (6-8 mg protein), 002 ml 

 of 0-5 M a-glycerol phosphate, and 0-4 ml 

 glycerol. Curve B represents the spectrum 

 of those pigments reduced by sodium 

 dithionite. The sample cuvette contained 

 a mixture of 0-4 ml of sarcosome pre- 

 paration (4-5 mg protein), a few crystals 

 of sodium dithionite, and 0-4 ml glycerol. 

 The reference cuvette contained a mixture 

 of equal volumes of glycerol and buffer. 

 Optical depth of cuvettes was 1 mm ; half 

 effective band width, 0-7 m^a; Condition 

 II. Temperature, -190°. 



WAVELENGTH (m^) 



Fig. 18. The low tem- 

 perature spectra of re- 

 duced haemoproteins of 

 wheat germ mitochon- 

 dria. Samples of mito- 

 chondria were treated 

 with various reagents, 

 mixed with an equal 

 amount of glycerol, and 

 cooled in liquid nitrogen. 

 Curve A represents those 

 pigments appearing on 

 the addition of Na2S204 ; 

 curve B is the pigments 

 reduced by succinate in 

 the presence of cyanide; 

 curve C represents the 

 absorption spectrum ob- 

 tained when no reducing 

 agent was added. Optical 

 depth equals 1 mm. Con- 

 dition II. 



