BIOLOGICAL TRANSPORT 



(1) 



ATP 



(2) 



(3) 



ADP-< 



Figure 17 The possible role of an enzyme in a group translocation. 

 See text for details. [From Mitchell, P., and Moyle, J. (1958), Nature, 

 182, 373; with permission.] 



The essential element emphasized by these authors is that ordi- 

 nary enzymes appropriately situated between phases may serve to 

 transfer groups from one phase to another and, with an appropriate 

 energy input, create concentration gradients. 



4 2 



