INDUCED ENZYME FORMATION 



per cell. Having purified the penicillinase and determined the 

 minimum turnover number, Pollock and Torriani (cited in 62) 

 were able to demonstrate that each molecule of penicillin thus 

 fixed can cause the formation of at least ten molecules of pen- 

 icillinase. These observations then establish that an inducer 

 can act catalytically. 



The unique feature of virtually irreversible adsorption of 

 inducer has thus far not been exhibited in other enzyme-forming 

 systems, and hence this type of experiment is at present feasible 

 only in the penicillinase-producing system. 



The Relatiofiship of Inducer to EFS 



The data reviewed thus far indicate that enzyme molecules 

 are fabricated on a template. Further, inducer molecules 

 appear to be specifically bound to some site concerned with 

 enzyme synthesis. Identification of the inducer-complexing 

 site with the template is the simplest and most economical hy- 

 pothesis at present worthy of further exploration. The question 

 naturally arises whether combination between template and 

 inducer leads immediately to full function. 



The least complicated variety of such an "activator" 

 hypothesis would assume that a full complement of templates 

 preexists and that the addition and adsorption of inducer mole- 

 cules is all that is required to convert them to complete activity. 

 This relatively simple model possesses several easily testable pre- 

 dictions. It would, for example, suggest that, providing other 

 conditions are not limiting, enzyme synthesis should proceed at 

 its maximal rate immediately subsequent to adsorption of in- 

 ducer. Further, once inducer molecules are adsorbed, one 

 would not expect on a priori grounds to find the emergence of 

 any strikingly different properties of the EFS as a consequence 

 of the accumulation of enzyme molecules. 



It is not too difficult to marshal evidence pointing up the 

 inadequacy of such activator mechanisms as suitable models of 

 induction. We may now consider the nature of this evidence 



131 



