Cell Structure and Metabolic Regulation 



33 



10- 



007 



006 



X».4X) 



•S^medium 

 hexo. 

 act. 



mi+o. hexo. act. 



released 



-005 



ao4 



-0.03 



002 



0.01 



u 

 -X3 



c 

 o 



o 

 _o 



E 

 o 



c 



D 

 O 



(^ 



d 



c 



O 

 >< 



0.2 0.3 0-4 0.5 



ml. hexokinase added 



06 



Fig. 12. Variations in hexokinase activity. The figure gives the variations in 

 hexokinase activity as a function of the amount of hexokinase added to a 

 mitochondrial suspension and then spinning the mitochondria down. Hexo. 

 sol. act. = activity of original solution of hexokinase ; medium hexo. act. and 

 mito. hexo. act. = activity of the enzyme in the medium and in the mito- 

 chondrial pellet after the mitochondria were spun down; ml. hexokinase 

 bound to mito. = calculated amount of hexokinase brought down with 

 the mitochondria; ip released = amount of inorganic phosphate in the 

 medium after the mitochondria were spun down and presumably due to the 

 small amount of contaminated microsomal glucose-6-phosphatase activity in 

 the large amount of mitochondria used. The figures in parentheses refer to the 

 increase in hexokinase activity which was brought down with the mitochondria 

 and it was calculated by comparing the obtained activity of the spun-down 

 mitochondria with the difference between the activity of the original hexokin- 

 ase solution and the activity of the hexokinase remaining in the medium after 

 spinning down the mitochondria. Data taken from Siekevitz and Potter 

 (1955) and unpublished experiments of Siekevitz and Potter. 



CELL METAB.— 2 



