. Bioenergetics. Bioenergetics. 43 ously, it produced cataract and most people prefer being fat or hungry to being blind. The mechanism of the action of dinitrophenol is the more puzzling because it acts not only on oxidative phosphorylation, but seems to act wherever energ}^ has to be transmitted and put to action. It inhibits various processes involved in photosynthesis and inhibits the "pumping activity" of cell membranes, in which os- motic or electric work is done. These reactions are so different that it was impossible to bring them to a common denominator OH N02 N02 (a) (6) Fi
. Bioenergetics. Bioenergetics. 43 ously, it produced cataract and most people prefer being fat or hungry to being blind. The mechanism of the action of dinitrophenol is the more puzzling because it acts not only on oxidative phosphorylation, but seems to act wherever energ}^ has to be transmitted and put to action. It inhibits various processes involved in photosynthesis and inhibits the "pumping activity" of cell membranes, in which os- motic or electric work is done. These reactions are so different that it was impossible to bring them to a common denominator OH N02 N02 (a) (6) Fig. 7. a: 2,4-Dinitrophenol. b: 2,4-Dinitro-l-naphthoI. in terms of chemistry. The only point at which all these reactions agree is that transmission of energy is involved, in one way or an- other. This makes it seem likely that the dinitrophenol is not in- volved in a definite chemical reaction, but acts rather through some physical principle, as is the quenching of E*. It may be interesting to note in this connection that both 2,4-dinitrophenol and 2,4-dinitro-l-naphthol (Fig. 7b) have in the near infrared a broad region of absorption. Dinitronaphthol is, essentially, dini- trophenol with an extra antenna added to it. McLaughlin and the author measured the quenching of the fluorescence of the aromatic hydrocarbon, chrysene, by a number of aromatic nitro derivatives and found dinitrophenol active and dinitronaphthol even more so. Unfortunately, their methods did not allow them to distinguish between true quenching and the simple competition for the light between quenching and quencher. So Karreman and Steele repeated these measurements with more adequate methods. Their results showed that both dinitrophenol and dinitronaphthol are true quenchers. The quenching observed. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the origin
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