76 



GENERAL METABOLISM 171 VltVO 



obtained with liver mitochondria (Kuff and Schneider, 1954). 

 Nevertheless, the bulk of the oxidative activity of the cell is 

 concentrated in particles of the mitochondrial fraction w^hich thus 



Dispersion 



SOO^lOmln 



Fraction II-Rj 



(Tissue fragments, whole cells, 



nuclei) 



Supernatant 



ISOO^lOmin 



1 



Fraction II-R, 



(Nuclei, mitochondria, 



a few whole cells ) 



Supernatant 



Fraction II-Rg 

 (Mitochondria) 



12,000^ 15 min 



Supernatant 



Fraction II-R4 

 Microsomes 



23,000^ 30 min 



Supernatant 



Fig. 10. The separation of subcellular fractions from dispersions 

 of whole brain. Diagram after Brody and Bain (1952). 



provides a cleaner preparation for the study of oxidative phos- 

 phorylation than does the whole dispersion. 



Mitochondrial preparations from whole brain contain mito- 

 chondria from many different types of cell and exhibit certain 

 differences in metabolism from liver mitochondria. Thus disper- 

 sion in 0-88 M aqueous sucrose, originally used in the preparation 



