li. L. AIRTH 271 



TABLE 1 



The Effect of Ultraviolet Light (3660A) on Fungal Luciferin 



AND LuCIFERASE 



Reaction conditions: luciferin, 0.20 ml; luciferase (0-75% (NHJ-jSOj fraction) 

 2.2 msj;; crystalline bovine plasma albumin, 10 me;; DPNH, 1.0 /nmole; 1% Tween 80, 

 0.1 ml; buffer, same as Fig. 2, to bring to a final volume of 3.0 ml. 



the reaction in terms of increase in light units per minute per milli- 

 gram of enzyme protein. Although the percentage changes in these 

 values are not identical, they do suggest a common trend. 



The lability, on exposure to ultraviolet light, of the active com- 

 ponent in the hot water extract — whether oxyluciferin or luciferin — 

 is quite apparent from these data. It has been found that exposures 

 as short as 15 minutes will reduce the activity by approximately 

 the same amount. Experiments have been conducted to determine 

 Avhether irradiated hot water extracts inhibit a reaction carried out 

 with non-irradiated substrate and enzyme. This does not appear to 

 be so- 



The data obtained with irradiated luciferase are not as convincing 

 as those discussed above. There is certainly a suggestion of stimula- 

 tion, and this aspect is being studied further. The response of the 

 mold to ultraviolet light is quite similar to that obtained with the 

 bacterial system. The similarity is even more striking when the re- 

 sults presented in Table 2 are considered. Both systems are in- 

 hibited by flavin derivatives. In fungi this is not a matter of inhibi- 

 tion due to the limiting hydrogen donor — DPNH. Contrary to the 

 bacterial system, however, the fungal system is not stimulated by the 

 addition of either reduced flavin mononucleotide (FMNHo) or flavin 

 adenine dinucleotide (FADHg) . The flavins were reduced by the 

 hydrogen paladium asbestos method. Here, inhibition could be due 

 to the presence of oxidized flavin. The bacterial and mold systems 

 also differ in that the latter in vitro reaction is not stimulated by 

 n-dodecylaldehyde. 



