670 



Comparative Animal Physiology 



strong support to the view that the aetual Hght-emitting molecule is the 

 luciferin. 



All our present knowledge of the properties of the bioluminescent process 

 appear capable of fitting into the following scheme of reactions.^"'- ^" 



Let A stand for luciferase, LH- for reduced luciferin (max. absorption, 

 435 m/x) and L for its oxidation products (max. absorption 465 m/x), L'^ 

 for excited luciferin, L, for destroyed luciferin. and X for an unknown fh. 

 donor, possibly glucose. 



1. 



2. 



3. 



4. 



5a. 



5b. 



5c. 



6. 



7. 



AL + XH.- 

 A + LH.— 



:ALH. + X 



ALH. + O.^ 

 ALH . 



iALH.. 

 =^ALU + H(X. 



AL + LH 

 AL + LH 

 AL- + LH 

 ALH + O. 

 AL + CX — 



:AL + H^ 



>AL* + LH- 



>AL + LH 



*AL, +LH- 



-* AL + LH- + hv 



-* AL + HO. 



-*AL, 



Essentially the same reactions, with the exception of reaction 2, also appear 

 to proceed in the absence of A, but their rates, especially that of reaction 5, 

 are such that no light is then produced. 



It is readily apparent from the foregoing scheme of reactions that only 

 reaction 5a is the actual lioht-emittinw one, but that this reaction is de 

 pendent on, or associated with, a number of other reactions which b\ them- 

 selves are dark reactions. The whole problem at the moment appears now 

 to be in such a state that one cannot sav with llnalitv whether it is lucifer- 



Mo MbO SOO 5M0 no '»60 SOO 540 



WAVELENGTH- mid 

 I iK- 25.^. C'lianKCs in the ahsoriition S|xctriiiii ol liiciliTin: A, iliiiinj; oxiilatinn with 

 DXNKfn uitliout hicilcrase (non-luniincscent), and H, in the presence ol lucilerase (hj^ht 

 |>r(itkicinK)- '" A eiirves H throuKli N were obtained after 9, 20, .-^0, 39. 49, 455, and 

 1 140 minutes, respectively. In />, curves \\ throus^li \ were obtained at 1.12. 22, 40, and 

 457 minutes. From (ohnson.'' 



