90 III. OXIDATION AND METABOLISM 



However, considerable evidence has been adduced to indicate that 

 diaciduria occurs when fatty acids having side chains are metabohzed. 

 Kuhn, Kohler, and Kohler" and Kuhn and Low^^ reported that a side chain 

 in the a- or the /3-position resulted in the formation of dicarboxylic acids. 

 Asano and Yamakawa^^ found that the yield of dicarboxylic acids was in- 

 creased by a factor of ten when side chains were present ; their work indi- 

 cated that a side chain at the a-position is as effective as one at the j8- 

 position in facilitating w-oxidation. Yamakawa^" also reported that 

 branched-chain fatty acids having sixteen or seventeen carbons first 

 underwent w-oxidation, and that this was followed by |8-oxidation, with the 

 liberation of two-carbon fragments. After 2-phenylstearic acid (CHs-- 

 (CH2)i5-CH(C6H5) -COOH) was injected into rabbits, Tamemasa^^ dem- 

 onstrated the presence of a-phenyladipic acid, HOOC -(0112)3 -011(06115) •- 

 OOOH, which presumably originated by c^oxidation and six ^S-oxidations 

 of the 2-phenylstearic acid. In another series of tests in which ethyl-2- 

 phenylstearic acid was injected into rabbits, Tamemasa^^ confirmed the 

 fact that 2-phenyladipic acid was excreted. However, a small amount 

 of «-phenylglutaric acid, HOOO-OH2-OH2-OH(06H5) -OOOH, was like- 

 wise identified. It was postulated that this might arise by dehydrogena- 

 tion of the stearic acid molecule at O9-O10, followed by oxidative cleavage 

 to a-phenylazelaic acid. The 2-phenylglutaric acid could then originate 

 as a result of 2 /S-oxidations. 



Flaschentrager ei al?^ believe that, when jS-oxidation is blocked by 

 substitution in either the a- or the j8-position, w-oxidation occurs as an 

 emergency mechanism for fatty acid oxidation. These workers are of the 

 opinion that this method of disposal of the fatty acid may be called into 

 play when no other pathway of oxidation is available, or when normal 

 processes are over-taxed by the administration of excessively large doses of 

 normal fats. Oarter^' suggests that the emergency theory of Flaschen- 

 trager et al?^ explains the striking cessation of oxidation which is known to 

 occur above lauric acid. Fatty acids having less than twelve carbon atoms 

 cannot be stored in the animal body, and hence must be oxidized as they 



" R. Kuhn, F. Kohler, and L. Kohler, Z. physiol. Chetn., 242, 171-197 (1936); 2J^7, 

 197-219(1937). 



's R. Kuhn and I. Low, Z. physiol. Chem., 259, 182-193 (1939). 



" M. Asano and T. Yamakawa, J. Biochem. {Japan), 37, 329-338 (1950). 



8» T. Yamakawa, J. Biochem. {Japan), 37, 343-353 (1950). 



81 O. Tamemasa, /. Pharm. Soc. Japan, 71, 101.5-1018 (1951); Chem. Abst., 46, 2149 

 (1952). 



82 O. Tamemasa, /. Pharm. Soc. Japan, 71, 1019-1024 (1951); Chem. Abst., 46, 2149 

 (1952). 



83 H. E. Carter, Biol. Symposia, 5, 47-63 (1941). 



