224 BIOCHEMISTRY OF BACTERIAL LUMINESCENCE 



erated in a light-producing reaction. Such mutations, since they prob- 

 ably involve at most only a few steps, could arise repeatedly in un- 

 related strains. This thesis necessitates no postulation of a special 

 luciferin since flavins, coenzyme I and perhaps aldehydes are ubiq- 

 uitous among living things. 



Evidence Concerning Mechanism of Interaction of Various 

 Components Required for Bacterial Extract Luminescence 



A number of lines of evidence are available which bear on the 

 relationship between the various factors necessary for in vitro lumi- 

 nescence. These studies are concerned with kinetic measurements 

 ( Strehler and Cormier, 1954b ) with the effect of various added com- 

 ponents on the respiratory rate (Strehler and Cormier, 1954a), with 

 the effect of reduced flavins on the luminescence with and without 

 added aldehyde (Strehler et ah, 1954) and some pressure effects ex- 

 amined in cooperation with Dr. Frank Johnson of Princeton Univer- 

 sity (Strehler and Johnson, 1954). 



Respiration 



Attempts to determine an effect of long-chain aldehydes on respira- 

 tion were at first unsuccessful, perhaps because the limiting reaction 

 either in the presence or absence of aldehyde is the DPNH2-FMN 

 reaction. However, it was possible, by varying the concentration of 

 oxygen in the medium, to show that the aldehyde did in fact affect 

 the level of luminescence and in a parallel manner the rate of respira- 

 tion at low oxygen tensions. The results of such studies are indicated 

 in the accompanying Fig. 10. From this figure it can be seen that the 

 luminescence as well as respiration — not shown) is accelerated at a 

 low oxygen tension, if aldehyde is added. The presence of aldehyde 

 changes the apparent Michaelis constants for oxygen (both for lumi- 

 nescence and respiration) by about a factor of 4. 



"Rise Time" Experiments 



Another type of kinetic study which was useful in determining the 

 relationships of the various components was the so-called % rise-time 

 experiment based on similar studies with Cijpridina extracts and in- 

 tact bacteria reported by Chance et al. (1940). The general design 



