848 LIGHT AND LIFE 



and the bacteria Achromobacter and Photobacterium. Additional in- 

 formation presented in this Symposium in regard to the biolumines- 

 cence of the sea pansy Renilla reniformis, the dinoflagellate Gonyaxilax, 

 and luminous fungi Armillaria mellea and Collybia velutipes provides 

 further comparisons with the classical examples. 



The Cypridina system is the simplest, involving only luciferin, luci- 

 ferase, water, and molecular oxygen. Cypridina luciferin is also 

 autoxidizable, without emission of light. It has been crystallized, 

 is yellow in color, and gives out a yellow fluorescence when exposed 

 to ultraviolet rays. Upon oxidation it yields an inactive red substance 

 and two colorless, blue-fluorescent oxyluciferins, one of which has been 

 crystallized, and is given the provisional structure: 



iCH=CH— N C— (CH2)3— NH— C— NH2 



o 



N o=C N NH 



OH CH 



I 

 CH 



/ \ 

 CH3 C2H5 



A. M. Chase and coworkers report studies on the oxidation of Cypri- 

 dina luciferin at different pH values, and its reduction by ascorbic 

 acid. They find that the troublesome difficulty in the preparation of 

 Cypridina luciferin owing to its ready oxidation in the presence of 

 dissolved oxygen is greatest at pH 9 and can be largely avoided at a 

 pH below 7, or somewhat less readily at a pH above 11. Ascorbic 

 acid was found to be a highly effective inhibitor of this non-lumines- 

 cent oxidation of luciferin. Even at pH 8.6, near the point of maxi- 

 mum instability of the luciferin, 0.01 M ascorbic acid almost com- 

 pletely prevents the autoxidation of the luciferin, and converts the 

 course of the luminescent reaction occurring when luciferase was 

 added from a complex to a first order relation. 



Firefly luciferin and oxyluciferin, as well as the enzyme luciferase, 

 have been crystallized and studied in consideraljle detail. The re- 

 duced luciferin is yellow and has a greenish yellow fluorescence. Un- 

 like Cypridina luciferin, it contains two sulfur atoms per molecule. 

 In the emission of light, it loses two hydrogen atoms to form oxyluci- 

 ferin, in a reaction requiring not only luciferase and oxygen, l)ut also 

 ATP and magnesium ions. Pyrophosj^hate is split off from the ATP, 

 and an oxyluciferin-enzyme-AMP complex is formed. 



