DAG LEY AND SYKES 



65 



assigned to malic dehydrogenase (Wolfe and Nielands [11]), of 64,000 to iso- 

 citric dehydrogenase (Dixon and Moyle [12]), and 204,000 to fumarase (Mas- 

 sey [13]; Cecil and Ogston [14]). If an estimate of 700,000 is taken as the 

 molecular weight of (3-galactosidase (Cohn [15]), the enzyme is certainly no 

 smaller than the 13 S component and its synthesis during adaptation to lactose 

 might well result in an addition to the pattern in this region. If this is also 

 true for the other induced enzymes it is surprising that they appear to be syn- 

 thesized in such quantity and that the molecules are so large that they sediment 

 between 13 and 20 S. 



It is sometimes stated that a number of enzymes are located in the 40 S 

 component, but this is not so for the activities we have investigated. In this 

 connection, observations on another system studied in these laboratories are 

 relevant (Callely, Dagley, and Hodgson [16]). Extracts have been prepared 

 from a vibrio which catalyze the oxidation of octanoate and other fatty acids 

 to acetate, apparently by the reactions of the fatty acid spiral (Lynen and 

 Ochoa [17]). If there are associations of related biochemical activities upon the 

 40 S particle analogous to those present in various particles from higher organ- 

 isms, they might well be sought here; but in fact the component may be re- 

 moved from these extracts with little diminution of the over-all rate of oxidation. 



en 



c 



c 



D 



E 



O 

 D 



o 



o 

 o 



5 



30 60 



Time of cenfrifuging, minutes 



90 



Fig. 2. Sedimentation of enzymes at 187,000^. Experimental points for: (3-galactosidase, 

 solid circle; citratase, square; glutamic decarboxylase, open circle. Arrow a shows time 

 when no lysine or arginine decarboxylase remained; and b, c, d, and e show levels of super- 

 natant activities after 90 minutes for fumarase, aconitase, isocitric dehydrogenase, and malic 

 dehydrogenase, respectively. 



