850 LIGHT AND LIFE 



teins (luciferases) , being from different species, are also different 

 to some extent, even though each is capable of reacting with the 

 Inciferin of the other organism. 



Other contributors to the Symposium on the subject of biolumines- 

 cence do not seem to share this view, or at least are non-committal 

 while emphasizing the distinctiveness of the systems they have been 

 investigating. 



The luminescence of cell-free fungal preparations from Armillaria 

 mellea and Collybia velutipies has been studied and reported by 

 R. L. Airth. Although E. N. Harvey was not able to obtain a cell- 

 free active luciferin-luciferase preparation from luminous fungi, it 

 may be accomplished by mixing a cold water extract containing the 

 luciferase with a hot water extract containing the luciferin, pro- 

 vided a reduced pyridine nucleotide is added. Either TPNH or 

 DPNH will serve, but the former is some 2.5 times as efficient. The 

 increase in light intensity during the course of the reaction is quite 

 slow. When subjected to purification procedures, the enzyme be- 

 comes rather unstable; addition of an emulsifying and dispersing 

 agent (Tween 80) stimulates both the initial rate of the reaction and 

 the maximum light intensity attained. The addition of bovine plasma 

 (or serum) albumin or of human albinuin also stimidates the reac- 

 tion, and reactivates the inactive enzyme, so as to produce a five-fold 

 increase both in light intensity and in rate of the reaction. Egg 

 albumin, gelatin, etc., will not do this. Optimal activity is at an al- 

 bumin/enzyme ratio of 2.5 to 4. When the reaction is started without 

 bovine albumin, and this protein is subsequently added, there is a 

 great increase in the rate of emission of light. Airth interprets these 

 observations in terms of an inhibition of the luciferase, which is re- 

 lieved by combination of the bovine albumin with the inhibitor. 

 Since McElroy et al. had found that irradiation with idtraviolet light 

 markedly enhances the emission of light by the bacterial biolumines- 

 cent system, Airth tested the effect of ultraviolet on the cell-free fungal 

 system. It reacted differently. There was, first, an inhibition of light 

 emission during the exposure, and then, after the exposure was ended, 

 a rapid increase up to a level some 70 per cent higher than the ori- 

 ginal level. It was demonstrated that the inhibition during the ir- 

 radiation is attributable to a labile component in the hot water ex- 

 tract, either luciferin or oxyluciferin; while the subsequent stinuda- 

 tion may be an effect on the irradiated luciferase. The action of 

 particular inhibitors suggests a metal requirement for the system. 

 At the present time, Airth suggests that the coniponcnt of the hot 



