84 



The Nature of Biological Diversity 



SCHEMATIC FORMATION OF ACETYL-CoA WITHOUT 

 ACETYL-AMP AS AN INTERMEDIATE 







// 



— — c — s 

 \ \ 



CH, CoA 



AMP 



i 







PP 



/ 



(Involves only one key transition state, without 

 shift in reactant binding for catalysis) 



FIG. 6. A scheme for the acetate thiokinase reaction with one key transition state. 



SCHEMATIC FORMATION OF ENZYME BOUND ACETYL-AMP 



AMP — 0-C 



CH 3 CoA 



(Involves two key transition states with shift of 

 position of bound reactants) 



FIG. 7. A scheme for the acetate thiokinase reaction with two key transition states. 



