856 LIGHT AND LIFE 



preparations from this organism in addition to oxygen, luciferin, 

 and luciferase, require a high concentration of sak. Although the 

 kiciferin and kiciferase will not cross-react with enzyme and substrate, 

 respectively, from other groups of luminous organisms, tkey were 

 found to cross-react with the enzyme and substrate of another related 

 species, Gonyaulax ynonilata. Gonyaulax cells, when agitated or 

 stimulated, emit bright flashes of light lasting less than one-tenth of 

 a second. A cell-free luciferin-luciferase preparation does not emit 

 light until a high concentration of salt is added. The enzyme has 

 been purified about 20-fold. The light intensity varies directly with 

 the enzyme concentration, but with increasing luciferin concentration 

 a typical saturation curve is obtained. A non-luminous nonenzymatic 

 oxidation of Gonyaulax luciferin also occurs. The product can be 

 reduced to active luciferin by means of cysteine or hydrogen, which 

 is not the case when luciferin is enzymatically oxidized. As the 

 enzyme concentration is increased there is a much higher total amount 

 of light from a given amount of substrate. This is interpreted as the 

 consequence of competition between the enzymatic and nonenzymatic 

 pathways of oxidation of luciferin. Bovine seriun albumin has a 

 marked stimulatory effect upon the emission of light, both as re- 

 spects intensity and total amount. Again, this is interpreted in terms 

 of the formation of an albumin-luciferin complex which protects 

 the substrate from the nonenzymatic oxidation. 



The salt requirement is absolute, and high concentrations, usually 

 about 0.8 M, are required for maximal light intensity. Many salts 

 are effective, both inorganic and organic. Others inhibit, and no 

 pattern to explain these differences is apparent. There is evidence 

 that the salt acts directly on the enzyme, since it affects its stability 

 and increases its rate of denaturation by heat. Salt also increases the 

 rate of the nonenzymatic oxidation of luciferin. The salt might, as 

 a third possibility, alter the quantum yield of the reaction by acting 

 on the excited state itself. To date, this has been neither demonstrated 

 nor excluded. 



A final report on a l:)ioluminescent system included in this Sym- 

 posium was made by iM. J. Cormier on the luminescence of the sea 

 pansy Re?nlla renifortnis, a coelenterate. Cormier strongly emphasizes 

 the biochemical distinctiveness of this system, and holds that luminous 

 forms of life have not only appeared sporadically during evolution 

 but have not evolved along the same biochemical lines. At first glance, 

 the Renilla luminous system appears very like that of the firefly, since 

 in addition lo luciferin, luciferase, and oxygen, a nucleotide is re- 



