200 



6. INTERACTIONS OF INHIBITORS WITH ENZYMES 



PROLIDASE 



CYTOCHROME C REDUCTASE 



ACETYLCHOLINESTERASE 



ANIONIC ESTERATIC 



SITE SITE 



ACETYLCHOLINESTERASE 



Fig. 6-2. Examples of some active centers and reaction mechanisms postulated 



for different types of enzymes. In all of these cases it may be observed that two 



more or enzyme groups are involved in the catalysis. 



Prolidase: The manganese ion chelates with the substrate which is also held by four 

 binding groups: Rj donates a proton during the transition period; Rj interacts through 

 van der Waals' forces with the — CHj — CH, — part of the ring; R3 interacts electro- 

 statically with the carboxylate group; and R4 catalyzes the hydrolysis and accepts a 

 proton. (Rabin, 1958, p. 21.) 



Cytochrome c reductase: This illustrates interaction between two components of the 



