64 



A SYMPOSIUM ON RESPIRATORY ENZYMES 



definitely diflFerent enzymes, one catalyzing the final step in the 

 oxidation of metabolites, the other catalyzing the oxidative inactiva- 

 tion of a part of the glycolytic system. 



This analysis seems a very promising approach at least to an 

 elucidation of the events taking place on the oxygen side. The simi- 

 larity between the respiratory and Pasteur enzymes suggests a direct 



400 450 500 550 600 m/ 



Figure 4. — Spectra of the respiratory and Pasteur enzymes 

 in animal tissue and in yeast 



reaction between oxygen and the transmitter. This is further in- 

 dicated by the difference in the affinity of the two enzymes for 

 oxygen (37, 47, 76). The peculiarities of the carbon monoxide effect 

 on respiration and a change of respiratory quotient at low oxygen 

 tension (37) and with carbon monoxide (38), however, seem to in- 

 dicate that the present interpretation may not represent the final 

 solution. 



In spite of the interest that attaches to the metal-specific anti- 

 catalysts, it should not be overlooked that such inhibitors as phe- 

 nosafranine, dinitrocresol (41), and glutathione can hardly be con- 

 sidered metal-specific. In an extensive study of the action of pheno- 



