PASTEUR EFFECT 63 



fermentation by inhibiting respiration was taken as indisputable 

 proof of the dependence of the Pasteur eflFect on the intactness of 

 respiration. Consequently ethyl carbylamine action, affecting only 

 the Pasteur effect, but leaving primary respiration intact, was in- 

 terpreted as inhibition of a reaction linking respiration to glycolysis. 

 A differential inhibition of respiration and Pasteur reaction by 

 carbon monoxide was observed by Warburg (43a) in yeast experi- 

 ments. Mainly interested in the respiratory effect of carbon 

 monoxide, he remarked only incidentally upon the relatively higher 

 sensitivity of the Pasteur reaction. Later, Laser (38) showed that 

 in animal tissues the differences in sensitivity were pronounced. Fre- 

 quently, he found, carbon monoxide had little or no effect on respira- 

 tion but did cause aerobic glycolysis to appear. The release of 

 aerobic glycolysis in animal tissues had been observed by Warburg 

 and Negelein (43), but had been considered as a secondary effect 

 due to inhibited respiration. From some preliminary measurements 

 of the effect of light on aerobic glycolysis in retina in the presence of 

 carbon monoxide, the spectrum of the Atmungsferment was charted. 

 Since Laser (38) had found respiration in retina to be uninfluenced 

 by carbon monoxide, these measurements, as Stern and Melnick (44) 

 recognized, had to be reinterpreted as preliminary measurements of 

 the spectrum of the Pasteur agent-carbon monoxide compound. 

 Stern and Melnick then measured carefully with the Warburg il- 

 lumination technique the relative absorption spectrum of the Pasteur 

 agent-carbon monoxide compound. The decrease in aerobic fer- 

 mentation on irradiation was plotted against wave length. This de- 

 crease may be assumed to be due to the decomposition of the 

 Pasteur agent-carbon monoxide complex. The resulting spectrum 

 was very similar to that of the respiratory enzyme. Such measure- 

 ments were made on retina (44) and yeast (45). Recently Melnick 

 (45a) charted the spectrum of the respiratory enzyme of animal 

 tissue by using heart muscle extracts in which, in contrast to the 

 intact tissue, respiration is sensitive to carbon monoxide (46). The 

 bands developed from these measurements are reproduced in 

 Figure 4. The spectra of the respiratory enzymes in yeast and in 

 animal tissue, respectively, differ greatly, as do those of the Pasteur 

 enzymes. In each case, however, the spectrum of the Pasteur enzyme 

 follows closely that of the respiratory enzyme, deviating only in the 

 absorption at longer wave lengths. The consistent, although small, 

 differences are considered as evidence of the existence of two 



