134 



SUBCELLULAR PARTICLES 



RELATIVE 

 CONCENTRATION 



0.8 - 



0.6 



0.4 



0.2 - 



O O URICASE 



X X ACID PHOSPHATASE 



A A CATHEPSIN 



V V ACID DEOXYRIBONUCLEASE 



+ + (^-GLUCURONIDASE 



A A PROTEIN 



V V GLUTAMIC 



DEHYDROGENASE 

 • • CYTOCHROME OXIDASE 



RADIAL DISTANCE . CM. 



I-® 



Fig. 3. Sedimentation diagrams in sucrose gradient. Washed total mitochondrial fraction 

 centrifuged according to the technique of Kuff et al. (58), but in a linear gradient of sucrose 

 ranging from 0.25 to 0.5 m over a railial distance from 5.4 to 9.6 cm. As demonstrated by 

 de Duve, Bcrthet and Reaufa\- (25), the sedimentation velocity of mitochondria is jiractically 

 independent of the radial distance in this gratlient. Time-integral of squared angular velocity 

 = 2.6 X lo** rad^ sec'\ 



We were able to back up this postulate by a limited number of correlations 

 between cytochrome oxidase, succinic dehydrogenase, rhodanese and the anti- 

 mycin-sensitive cytochrome c reductases, and between glucose-6-phosphatase and 

 the antimycin-insensitive cytochrome c reductases. To the list of enzymes obeying 

 the postulate of homogeneity we may now add glutamic dehydrogenase, malic 

 dehydrogenase and alkaline deoxyribonuclease (DNA-ase I) in the mitochondrial 

 group (6; see figs. 3-6) and in the microsomal group aryl-sulphatase C (39) and 

 esterase (100). In addition, two more facts may be marshalled in support of the 

 distinction between the particles bearing acid phosphatase and the oxidizing 

 mitochondria; namely, the results of figures 5 and 6, showing that the two 

 groups can also be largely dissociated on the basis of their density in solutions 

 of sucrose in heavy water (6); and those of figures 7 and 8, indicating that the 

 release ol a soluble mitochondrial enzyme does not follow that of acid phos- 

 phatase, when brought about by a decrease in tonicity or repeated freezing and 

 thawing (9). Apparently arguing against our interpretation is the fact that the 



