BERNARD L. STREHLER 229 



thought hkely that reduced FMN should support luminescence quite 

 as well as the oxidized flavin plus reduced DPN. This was found to 

 be the case (Strehler et al, 1954). Moreover, it was noted that maxi- 

 mal luminescence in the presence of reduced flavins and rapid rises 

 to the high level of luminescence as well as rapid utilization of the 

 reduced flavins occurred only in the presence of aldehyde. Thus, the 

 aldehyde functions subsequently to FMN reduction (see Fig. 12). 



In these studies we found that reduced riboflavin as well as reduced 

 FMN will support luminescence, and we have recently reported this 

 to be true. However, further studies by Dr. Harvey (personal com- 

 munication) and Dr. McElroy (personal communication) independ- 

 ently have shown that the effect of adding reduced riboflavin to the 

 system may be an indirect one although the time required for the re- 

 action is relatively short and of the same order of magnitude as the 

 time required for luminescence to become half -maximal when reduced 

 FMN is added. Perhaps the reduced riboflavin reacts with the reduced 

 FMN or possibly the reduced riboflavin can react equally well as 

 FMNHo in one of the steps. However, reduced FMN may be required 

 for another step either because of enzymatic specificity or because 

 the phosphate group may be required for the formation of an active 

 chemically conjugated intermediate as McElroy has suggested (per- 

 sonal communication). Harvey has also tested a number of other 

 compounds closely related to reduced FMN such as reduced FAD, 

 lumichrome, reduced lumiflavin, and several nonmetabolic flavins. As 

 indicated in comment, he found that flavin mononucleotide was re- 

 quired for the luminescent reaction to occur at high rates. 



Pressure Effects 



A large amount of effort has been expended over a number of years 

 on the effects of pressure on the luminescence of intact luminous bac- 

 teria by Johnson, Eyring, and their collaborators (1942, 1945, 1947, 

 1954). Dr. Johnson will discuss in more detail some of the observa- 

 tions I am going to mention. However, inasmuch as they are con- 

 sistent with and suggest an interpretation for some of the other 

 observations mentioned above, it is fitting that they should be pre- 

 sented briefly. The main results in idealized form are abstracted in 

 Fig. 13. When pressure is applied either to intact bacteria or to lumi- 



