106 III. OXIDATION AND METABOLISM 



(d) Fatty A cid Oxidase of Kalnitsky and Barron. Kalnitsky and Barron ^^° 

 prepared a fatty acid oxidase system from rabbit kidney which strongly 

 oxidized a number of fatty acids, inchiding acetic, butyric, /3-hydroxybu- 

 tyric, crotonic, vinylacetic, a-ketovaleric, methylethylacetic (CHa-CH- 

 (C2H5)-COOH), caproic and a-ketocaproic acids. On the other hand, 

 formic, propionic, and a-hydroxybutyric and a-ketobutyric acids were oxi- 

 dized slowly. The oxidase lost its potency in five hours, except toward ca- 

 proic and a-ketocaproic acids. Fluoroacetate and fluorobutyrate inhibited 

 the oxidation of most of the acids. 



(e) Fatty Acid Oxidation According to Green and Mii. Green and Mii,^^^ 

 and others, ^^^~^^'* have outlined the present theories (1954) of fatty acid 

 oxidation in animal tissues, in terms of the enzymes required and the reac- 

 tions catalyzed, as described below: 



a' . Activation Enzymes. These catalyze the formation of acyl-CoA from 

 the free fatty acid, with the concomitant change of ATP to AMP (adeno- 

 sine monophosphate), and the formation of pyrophosphate. Mahler, 

 Wakil, and Bock"^ prepared a highly purified form of the agent which ac- 

 tivates fatty acids (FAAE), from beef liver. This agent catalyzes the for- 

 mation of acyl CoA from a wide variety of fatty acids in the presence of CoA 

 and ATP. At least three different enzymes act on the acyl CoA compounds 

 with various specificity ranges covering the gamut from C4 to Cis. 



(a') Butyryl Coenzyme A Dehydrogenase. — Green, Mii, and Mahler^^^ 

 isolated and purified the enzyme which mediates the first step in the oxida- 

 tion of the lower fatty acids ; this acts at a maximal rate on butyryl CoA, 

 and hence the name butyryl CoA dehydrogenase is proposed for the pro- 

 tein. Mahler '^^ reported that this enzyme is a cuproflavoprotem containing 

 1.2% (by weight) of riboflavin, and 0.345% of copper. The copper: flavin 

 ratio was found to equal 2. The flavin part of the prosthetic group has been 

 shown to be identical with flavin-adenine-dinucleotide (FAD). Mahler ^^* 

 prepared a copper-free enzyme by dialysis against cyanide which was still 



i«o G. Kalnitsky and E. S. G. Barron, Arch. Biochem., 19, 75-87 (1948). 

 161 D. E. Green and S. Mii, Federation Proc, 12, 211 (1953). 

 i«2 D. E. Green, S. Mii, and H. R. Mahler, /. Biol. Chem., 206, 1-12 (1954). 

 1" H. R. Mahler, /. Biol. Chem., 206, 13-26 (1954). 

 i«^ S. J. Wakil and H. R. Mahler, /. Biol. Chem., 207, 125-132 (1954). 

 i«6 S. J. Wakil, D. E. Green, S. Mii, and H. R. Mahler, J. Biol. Chem., 207, 631-638 

 (1954). 



166 H. Beinert, /. Biol. Chem., 205, 575-584 (1953). 



1" S. Wakil and H. R. Mahler, Federation Proc, 12, 285 (1953). 



168 D. S. Goldman, /. Biol. Chem., 208, 345-357 (1954). 



169 P. Hele, /. Biol. Chem., 206, 671-676 (1954). 



1™ A. Millerd and J. Bonner, Arch. Biochem. Biophys., 49, 343-355 (1954). 



I'l H. R. Mahler, S. J. Wakil, and R. M. Bock, J. Biol. Chem., 204, 453-468 (1953). 



