54 Essays in Biochemistry 



it retains moist of its activity at 38° for 24 hours, and it is not. inac- 

 tivated by glutathione or ascorbic acid. 



Unfortunately, we could not determine unequivocally whether this 

 organic inducer could, in contrast to direct irradiation, induce bacteria 

 which had been rendered inapt by starvation. The photolytic products 

 are effective only if they are in contact with the organism for 40 to 

 50 minutes. At the same time the lacking nutrient must be provided 

 to enable the induced organism to elaborate phage and the organisms 

 are known to regain aptitude under these conditions. 



Although we pay constant heed to the devil's advocate who per- 

 sistently insinuates that the unique effect of irradiated leucovorin is 

 an artefact, unrelated to true induction, there are circumstantial indi- 

 cations which entice one to pursue the study of the phenomenon: 

 leucovorin is heavily implicated in purine metabolism 19 and the photo- 

 lytic product of folic acid, 2-amino-4-hydroxy-6-formylpteridine, is 

 known to be an extremely potent inhibitor of xanthine oxidase. 20 At 

 any rate, the phenomenon may not be without value as a possible tool 

 to explore induction: the effect of the photolytic products on isolated 

 enzyme systems can be studied, and its possible concentration in some 

 component of the cell can be explored. 



There are, of course, a host of possible mechanisms for the develop- 

 ment of inaptitude other than the loss of a radiation-sensitive co- 

 factor of induction. However, we shall refrain from listing any of 

 these. The writer is shackled by his own injunction to overly imag- 

 inative students: fruitful biochemical speculation must stand on a 

 bifurcated root, one reaching into the biological phenomenon, the other 

 into the store of immediately applicable methods of chemical explora- 

 tion; otherwise such speculation is not biochemistry. Unfortunately, 

 we have not been able to nourish the second root too well. 



We must finish this essay, as we started, on hope, a hope that the 

 goal may be reached when a detailed series of reactions can be written 

 for the chemical events that are precipitated when an inducible lyso- 

 genic organism is exposed to a packet of inducing energy. The writer 

 is conditioned to grope for such a goal, for he belongs to what he likes 

 to call the Hudson River School of biochemistry. Should the name 

 the Hudson River School evoke in the reader's mind an association 

 with the school of painting of the same name, the writer would be 

 neither surprised nor displeased. For it must be recalled that the 

 painters of the Hudson River School painted every tree, every twig, 

 every leaf into a landscape. So, too, the school of biochemistry 

 founded by the man to whom this book is dedicated strives for the 



