w. D. Mcelroy and j. w. Hastings 



169 



The product of the oxidation of luciferin is, likewise, a potent in- 

 hibitor of the Hght reaction. Preparations of oxidized kiciferin when 

 added to reduced luciferin completely and apparently irreversibly 

 inhibit light emission. The inhibitory effects can be prevented by add- 

 ing crude protein preparations to the luciferin mixture before mixing 

 with luciferase. ApparenUy the protein selectively adsorbs oxidized 



L 



TABLE II 



COMPOUND 



I BENZIMIOAZOLE 



5-METHYL 



5,6 - DIMETHYL 



|-=t-0-RIBOFURANOSIOO- 

 5,6 -DIMETHYL — 



2 INDOLE 



3 -METHYL 



1,3-DIMETHYL 



ETHOX Y 



INDOLE ACETIC ACID 

 TRYPTOPHANE 



3. BENZOTHIAZOLE 



2 -CHLORO — 



2- AMINO 



2 - PHENYL 



2 - MERCAPTO 



4 8ENZ0TRIAZ0LE 



5 BENZOXAZOLE 



PARENT 

 STRUCTURE 



/N^'^c 



2 

 II 



3n 



/V">c 



2' 



II 

 3C 



/\/N 



CONC 50 PERCENT 

 INHIBITION MOLAR 



1 9 X 10 



6 5 X lO'* 



2 4 X 10"* 

 NON- INHIBITOR 



3 5 X 10 ^ 



4 X 10'* 

 NON- INHIBITOR 

 NON - INHIBITOR 

 NON - INHIBITOR 

 NON - INHIBITOR 





/V°\ 



26 X 10"* 

 4.7 X ID'S 



BOX 10'* 

 3 3 X 10'^ 

 NON ■ INHIBITOR 



I 6 X 10 



-3 



67 X 10 



-4 



luciferin. Once the inhibition occurs, however, it cannot be reversed 

 by adding the protein to the reaction mixture. Coenzyme A appears 

 to be able to remove the oxidized luciferin from the luciferase since 

 the addition of this cofactor after light initiation will stimulate 

 luminescence (McElroy, unpubhshed). The secondary response to 

 coenzyme A, under the conditions described, appears to be specific 

 and has been used in the study of Co A synthesis. 



