BERNARD L. STREHLER 



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DILUTION FACTOR 

 Fig. 2. Effect of dilution of bacterial enzyme extract on luminescence. Each 

 tube contains: 600 /xg DPNHo, 0.2 ml phosphate buffer, 0.01 M, pH 7.0; 

 0.3 ml of stock extract or of diluted extract (diluted just before measure- 

 ment). Total volume, 0.6 ml. Stock extract: 13 g acetonized powder in 100 

 ml of water, centrifuged 1 hour at 0° C on Serval centrifuge at 12,000 rpm. 

 Gross luminescence was multiplied by dilution factor to obtain luminescence 

 per unit weight of enzyme. 



malic acid, thiamin pyrophosphate, and Mg+ + . Riboflavin, naphtho- 

 quinone, and FAD were "powerful inhibitors of luminescence, the 

 Others either initiating or increasing light production under various 

 conditions. 



In the presence of DPNH2, only, FMN, of the defined compounds, 

 had a potentiating effect (Strehler and Cormier, 1953). DPN or 



