104 III. OXIDATION AND METABOLISM 



from different animals. In the rat, activation of the octanoate oxidation by 

 hver mitochondria was brought about by ATP or by a system generating 

 ATP. However, when kidney and hver mitochondria obtained from the 

 rabbit were used, the oxidation of octanoate could not be sparked by ATP 

 unless the w-oxidation of an intermediate of the citric acid cycle occurred 

 concomitantly. The action of 2,4-dinitrophenol (DNP) in inhibiting fatty 

 acid oxidation was shown to be due to its action in preventing ATP syn- 

 thesis. The action could be overcome by using an excess of ATP. Appel 

 and Kiese^^'* confirmed the fact that the sparking effect of the citric acid 

 cycle is necessary to enable the Lehninger enzyme system^ ^^ to function in 

 the anaerobic decomposition of caprylic acid. These workers demon- 

 strated the decomposition of one out of ten micromoles of the acid when 

 ten to twenty micromoles of methylene blue were also added to the system 

 along with the enzyme. 



d' . Oxidative Phosphorylation and Fatty Acid Oxidation : Oxidation of 

 fatty acids has been shown to be accompanied by an oxidative phosphoryla- 

 tion. Johnson and Lardy ^^^ reported that the oxidation of acetate, butyr- 

 ate, caprylate, and crotonate by washed residue of rabbit kidney homoge- 

 nate in the absence of fluoride is accompanied by a net uptake of orthophos- 

 phate. P:0 ratios of 1.0 to 1.7 were noted. In contradistinction to these 

 results, the P:0 ratios were approximately 3.0 for pyruvate, acetoacetate, 

 and /3-hydroxybutyrate, in the presence of fluoride, and 1.0 to 1.5 in its ab- 

 sence. Fluoride inhibits fatty acid oxidation at some step prior to the for- 

 mation of the /3-keto-acid and subsequent to the oxidation of the unsat- 

 urated acid. Gillette and Kalnitsky^^^ suggest that fluoroacetate inhibits 

 oxidation at the point of primary oxidation of the fatty acid to the 2-C 

 intermediate. It is believed that this is accomplished by removing Mg++, 

 since it was shown that Mg++ and sodium fluoroacetate can form a stable 

 complex. The formation of fluorocitrate is likewise suggested as a possible 

 cause of inhibition. This type of inhibition can be overcome by the addition 

 of an excess of Mg++. 



(6) Cyclophorase Preparations. Green and co-workers ^^^ referred to 

 their preparations of the well-washed, easily sedimented particulate matter 

 of liver and kidney, which is insoluble in approximately isotonic KCl solu- 

 tions, as "cyclophorase." Their material was shown to bring about a 



1" W. Appel and M. Kiese, Biochem. Z., 322, 156-164 (1951). 

 155 R. B. Johnson and H. A. Lardy, ./. Biol. Chem., 184, 235-242 (1950). 

 i5« J. R. Gillette and G. Kalnitskv, ./. Biol. Chem., 187, 679-686 (1950). 

 >" D. E. Green, W. F. Loomis, and V. H. Auerbach, /. Biol. Chem., 172, 389-403 

 (1948). 



