266 VI. ACETIC, FORMIC, AND PROPIONIC ACIDS 



ever, acetylation will proceed under anaerobic conditions if an "energy- 

 rich" phosphate source such as adenyl pyrophosphate is present.^^ This 

 may function by brmging about the formation of acetylphosphate. 



A different enzyme is required for acetylation of a-ammo acids than for 

 sulfanilamide. This enzyme was found to be present in much higher con- 

 centration in slices of rat liver than m those of gumea pig or pigeon liver. ^ 

 This enzyme brought about acetylation, not only of L-phenylammobutyric 

 acid, but also of the natural amino acids, leucine and phenylalanine.^' 



b. Formation of Mercapturic Acid. When cysteine is employed for the 

 detoxication of bromobenzene, acetylation apparently precedes the forma- 

 tion of p-bromophenyl mercapturic acid,^^ which is the end-product excreted 

 in the urine. 



HSCH2 /<: S • CH2 



HCNHCCOCHs) > HCNHCCOCHs) 



I \) I 



COOH Y COOH 



Acetylcysteine p-Bromophenylmercapturic 



acid 



Synthesis of p-Bromophenylmercapturic Acid 



According to Stekol, mercapturic acids are formed after the admmistration 

 of p-bromobenzyl bromide,^* monobromobenzene,^^"** naphthalene,*^"^' 

 anthracene,^' ~^- and benzyl chloride.^' The sjnithesis of mercapturic 

 acids has been reported in many species of animals, includhig mice,*^ 

 rats,87.88.9o-94 rabblts, 87-89,92,93,95-97 ^^ts, »« dogs,*^-*'''^''^"-'^'' and swine.«^'»« 



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85 J. A. Stekol, Proc. Soc. Exptl. Biol. Med., 33, 115-119; 119-121 (1935). 



86 J. A. Stekol, J. Biol. Chem., 117, 147-159 (1937); 118, 155-lGO (1937). 

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88 J. A. Stekol, /. Biol. Chem., 121, 87-91 (1937). 



89 J. A. Stekol, /. Biol. Chem., 110, 463-469 (1935). 



90 J. A. Stekol, J. Biol. Chem., 122, 333-342 (1938). 



91 J. A. Stekol, /. Biol. Chem., 124, 129-133 (1938); 128, 199-205 (1939). 



92 E. Bovland and A. A. Levi, Biochem. J., 30, 1225-1227 (1936). 



93 N. R. Lawrie, Biochem. J., 25, 1037-1044 (1931). 



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96 M. C. Bourne and L. Young, Biochem. J., 28, 803-808 (1934). 



9' K. Nishimura, Ada Schol. Med. Univ. Kioto, 12, 73-78 (1929); Ch&m. Abst., 24, 

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98 R. W. Virtue, Proc. Soc. Exptl. Biol. Med., 34, 425-427 (1936). 



99 E. Baumann and C. Preusse, Ber., 12, 806 810 (1879). 

 '™ M. Jaffe, Ber., 12, 1092-1098 (1879). 



