MILTON J. CORMIER 



281 



Thus the hiininescent reaction involves a nucleotide-dependent 

 oxidation of hirifcrin. Indeed, some preliminary observations on the 

 properties of lucilerin indicate that it is oxidizable under certain 

 conditions. For example, luciferin activity is destroyed by heating 

 at lOO^C for 1 minute in the presence of 0.06 A^ HCl and oxygen, 

 but is stable at this temperature and HCll concentration providing 

 the system is kept anaerobic. 



An enzyme system whose luminescence has been allowed to decay 

 to a negligible level in the presence of nucleotide can be treated 

 with ammonium sulfate to precipitate the enzyme, and the latter 

 (resolved enzyme) can be used as an assay for the unknown factor. 

 When this is done, the eflfect of increasing concentrations of boiled 

 extract on the light intensity can be studied. The results (Fig. 4) 

 show that 80-fold stimulations of luminescence were observed upon 

 the addition of sufficient amounts of crude luciferin. No increase 

 above background is observed in the absence of added nucleotide. 

 The apparent saturation at higher levels may be due to inhibitors of 

 luminescence in the boiled extract. Luciferin cannot be replaced by 

 divalent cations such as magnesium or manganese and many others 

 that were tested. No luciferin activity could be demonstrated upon 

 the addition of long-chain aldehydes which are involved in bacterial 



2 50- 



0.3 



o;4 



CRUDE LUCIFERIN ADDED (ml.) 

 Fig. 4. Effect of luciferin concentration on luminescence. 



