310 LIGHT AND LIFE 



ously. Dr. Chase has said that he has been able to run this in the presence 

 of huge amounts of ascorbic acid, which we know is an autoxidizable sub- 

 stance utilizing oxygen, without any decrease in the rate of luminescence or 

 having any influence at all on the rate of luminescence. I wonder if this 

 should not have some influence if this is an absolute oxygen-requiring 

 system. 



Dr. Chase: Actually, the ascorbic acid seems only to be causing the reduc- 

 tion of oxidi/ed luciferin so that it will give bright light when luciferase is 

 added. I don't believe the autoxidation of ascorbic acid in the absence 

 of the oxidase would be fast enough at 26 °C and pH 8 to reduce the concen- 

 tration of dissolved oxygen enough to affect luminescence in this system. 

 Would you agree with that. Dr. McElroy? 



Dr. McElroy: That's right. As a matter of fact, you get maximal 

 luminescence in the firefly system with approximately 0.05% of oxygen 

 and the same way in the Cypridina system. 



Dr. Hastings: It isn't quite the same as Cypridina. 



Dr. McElroy: No, in Cypridina the luminescence is decreased at higher 

 oxygen concentrations than in the firefly. 



Dr. Hastings: That's correct. If you decrease the oxygen concentration 

 below that of air— which is 20%— even by just a little, the luminescence of 

 Cypridina decreases. Luminescence intensity is a continuous function with 

 oxygen concentration from zero to 20%. I think, Dr. Udenfriend, that the 

 answer to your question lies in the fact that Dr. Chase probably does his 

 experiments by incubating luciferin in ascorbic acid and then taking out 

 aliquots for assay— which would dilute the ascorbate and it would then have 

 a negligible effect. 



Dr. Chase: No, I don't think that's it. The dilution was only one in 

 three, which wouldn't reduce the ascorbic acid concentration enough to make 

 iiuuh difl'crence. 



Dr. Hastings: Does it highly autoxidize rapidly or is it fairly slow? 



Dr. Chase: Well. I don't think it autoxidizes much under these particular 

 conditions. I tliink that what oxidation occurs is from the reduction of the 

 luciferin. The oxygen concentration shouldn't be affected. 



Dr. Vei.ick: People often refer to effects produced by tris buffer, obscuring 

 the possibility tliat the anion of the buffer may be the culprit. For example 

 the fluorescence quantum yield of DPNH in the glyceraldehyde-3-phosphate 

 dehydrogenase complex is diminished in tris acetate and enhanced lightly 

 in tris phosphate. In the LDH complex the DPNH emission is enhanced by 

 acetate. 



Dr. Hastings: The anion in our tris buffer was maleate. 



Dr. (Iormu-.r: Just a couple of comments. I wouldn't want us all to go 

 away thinking that salts are required for all marine bioluminescence, because 

 this is certainly not the case with the sea pansy. As you approach distilled 

 water you are much better off. The other comment I would like to make 



