STUDIES ON BIOLUMINESCENCE. 



XII. The Action of Acid and of Light in the Reduction of 

 Cypridina Oxyluciferin. 



By E. NEWTON HARVEY. 

 (From the Physiological Laboratory, Princeton University, Princeton.) 



(Received for publication, October 17, 1919.) 



In the luminous crustacean, Cypridina, a substance, luciferin, is 

 oxidized in the presence of water, oxygen, and another substance, 

 luciferase, with the production of light. I have called the oxidation 

 product of luciferin oxyluciferin; it is obtained by allowing luciferin 

 in solution to oxidize completely. The oxidation is accelerated at 

 high temperatures. An extract of Cypridina, boiled until it no 

 longer gives light on mixing with luciferase, will be spoken of through- 

 out this paper as an oxyluciferin solution (Harvey, 1918-19). A 

 solution of oxyluciferin has the same reaction as a luciferin solution. 

 It is shghtly alkahne, about pH = 9. 



No measurable production of CO2 (Harvey, 1919-20, a) or of 

 heat (Harvey, 1919-20, b) accompanies the oxidation of luciferin. 

 The reaction, luciferin — ^ oxyluciferin, therefore involves a relatively 

 slight energy change and should be readily reversible. An oxyluci- 

 ferin solution, however, will not reduce to luciferin spontaneously on 

 standing (in the dark) or on removal, with an air pump, of the dis- 

 solved oxygen. However, if we add to an oxyluciferin solution some 

 milk, frog muscle suspension, yeast cells, bacteria, or Mg powder plus 

 acid, which results in the evolution of nascent hydrogen, luciferin 

 will be formed and can be tested by its abihty to luminesce with 

 luciferase. As the reducing action of milk, tissues, bacteria, and 

 nascent hydrogen are so well known, it seemed probable that they 

 formed luciferin by removal of oxygen from, or addition of H2 to, 

 oxyluciferin, reducing it in the same way that methylene blue can be 

 reduced (decolorized) by tissue cells, bacteria, nascent hydrogen, etc. 



In my previous paper (1918-19) I called attention to the fact that 



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