292 LIGHT AND LIFE 



or AMP. Since the DEAE fractions do not contain significant ADPase 

 activity, ho\vever, it follows that ADP is functional in this system 

 without first being converted to AMP. Furthermore, it seems un- 

 likely that luciferase would non-specifically utilize either AMP or 

 ADP, but not ATP, for light production. Thus AMP may be in- 

 volved in this system via a cyclic phenomenon that results in the 

 formation of ADP. In order to satisfy the kinetic data, however, one 

 would have to assume that the equilibrium of the reaction leading to 

 the formation of ADP from AMP lies far in the direction of ADP. 



An example of a cyclic mechanism of the type discussed would be 

 one involving the intermediate formation of luciferyl phosphate from 

 ADP and luciferin. The product of this reaction, AMP, might then 

 react, after the light reaction, with oxyluciferyl phosphate to form 

 ADP and oxyluciferin. This mechanism, of course, is purely specida- 

 tive and simply provides a working hypothesis for future investigations. 



The data do not rule out a nucleotide-dependent enzymic release 

 of bound luciferin. It is difficult with such a mechanism, however, 

 to visualize a cyclic scheme that would explain the activity of both 

 nucleotides in this reaction. 



Acknowledgments 



The author wishes to acknowledge the competent technical assistance of Mrs. 

 R. J. Eckroade during the course of tliese investigations. In addition, these studies 

 would not have been possible without the aid and close cooperation of Drs. 

 J. M. Teal and L. R. Poineroy of the University of Georgia Marine Institute, 

 Sapelo Island, Georgia, during the collection of the animals used in these experi- 

 ments. The author also wishes to express his appreciation to Dr. R. \. McRorie 

 for his helpful criticisms and suggestions during the preparation of the manuscript. 

 The author wishes to express his appreciation for the generous gifts of firefly 

 and Cypridina luciferins by Drs. W. D. McElroy and E. N. Harvey, respectively. 



REFERENCES 



1. Airth, R. L., and McElroy, W. D., /. BacterioL, 77, 249-2.")0 (ID.'iO). 



2. Cormier, M. J., /. Am. Cliem. Sor., 81, 2592 (19r)9). 



3. Cormier, M. J., Bioc him. el Biophxs. Acta (in press). 



4. Cormier, M. ]., and lottcr, ]. R., Biodiiiii. el Bi(>l>liy.s. Ada. 2.5, 229-237 



(1957). 



5. Cormier, M. J., Totter. J. R.. and Rostorler. II. H., .-ixh. Biochem. and 



Biof)liys., 63, 414-426 (1956). 



6. Fiskc, C. H., and Suhharow, Y., /. Biol. Chem.. 66, 375.386 (1925). 



7. Har\cy, E. N., Binhiminr.srcnce. .Academic Press, New ^'ork (1952). 



8. Hastings, J. W.. and McElrov, ^V. D., in The I.iimiiu'scence of Biological 



Syslem.s (F. H. Jolnison. ed.). pp. 257-269, American .Association for the 

 .Athancemcnt of .Science, Wasliinglon, D. C. (1955). 



9. Hurlbert, R. B., .Schmitz, K., Brumm, A. F., and Potter, V. R., ,/. Bio!. 



Chem., 209-221, 23 (1954). 



