E. NEWTON HARVEY 211 



NaHaPOz + H2O + Pd = NaHaPOs + H2 + Pd 

 (Sodium hypophosphite) (Sodium phosphite) 



This reaction occurs in the presence of finely divided palladium. 

 The methylene blue is reduced by the H2, and the hypophosphite is 

 oxidized. Since oxyluciferin can be reduced by palladium and 

 sodium hypophosphite (Harvey 1918-19), it is probable that we can 

 write the equation for the reduction of oxyluciferin and oxidation of 

 luciferin in a similar manner to that of methylene blue. 



Luciferin + O ?^ oxyluciferin + H2O 

 More briefly 



LH2 + O ^ L + H2O 



Just as in the case of methylene blue the reaction proceeds in the 

 right hand direction spontaneously if the pressure of O is sufficiently 

 high. If luciferase is also present we have luminescence. . 



LH2 + O + luciferase <=:^ L + H2O + luciferase (luminescence) 



The reaction proceeds in the left hand direction under low oxygen 

 pressure, in the presence of nascent hydrogen, or with some catalyzer 

 which is able to spHt water, transferring the H2 to oxyluciferin and 

 the O to an acceptor (A). NaH2P02 plays the part of the acceptor. 



L + H2O + A + Pd <=^ LH2 + AO + Pd 



This appears to be the way in which the reducing enz3nnes or 

 perhydridases (comparable to the Pd) of living tissues act (Bach, 

 1911, 1912, 1913), and the action of yeast cells, bacteria, muscle 

 suspensions, etc. in reducing oxyluciferin must occur in the same 

 manner. 



If we assume that the LH2 (luciferin) compound is dissociated even 

 to the slightest extent into L and hydrogen, the hydrogen ion will 

 shift the equihbrium toward the formation of that substance which 

 involves the taking up of hydrogen. Consequently we may obtain 

 a partial formation of luciferin by adding an acid to oxyluciferin. 

 Reduction of the hydrogen ion concentration tends to shift the equi- 

 hbrium in the opposite direction. Consequently, addition of alkaH 

 favors the oxidation of luciferin and it is quite generally true that 

 biological oxidations are favored by an alkahne reaction. In addi- 



