780 URINE. 



The aromatic amino-adds are, like the amino-acids in general, decom- 

 posed to fatty acids and have one carbon atom less. For example phenyl- 

 amino-acetic add is in part converted into benzoic acid (O. NEUBAUER); 

 o- and w-tyrosine yield o- and m-oxyphenylacetic acid respectively 

 (BLUM, FLATOW); p-chlorphenylalanine passes according to FRIEDMANN 

 and MAASE into p-chlorphenylacetic acid, and phenyl-a-aminobutyric 

 acid is changed, as KNOOP 1 showed, into phenylpropionic acid. As 

 intermediary steps in this demolition we have, as in the other amino-acids, 

 part the hydrolytic cleavage of NH2 groups and part the demolition by 

 way of the corresponding keto-acid. 



As an example of a demolition of the first kind we have for a long 

 time considered the finding by SCHOTTEN, of mandelic acid 



C 6 H 5 .CH(OH).COOH 



in the urine after feeding phenylaminoacetic acid, Cells. CH(NH2).COOH. 

 According to O. NEUBAUER 2 the process is nevertheless of another kind, 

 namely, mandelic acid is produced secondarily by reduction from the 

 intermediarily formed keto-acid, phenylglyoxylic add, CeHs.CO.COOH. 

 As example of a hydrolytic deamidation we will use the production, as 

 first observed by BLENDERMANN, of p-oxyphenyl-lactic add, 



HO.C 6 H 4 .CH 2 .CH(OH).COOH 



from tyrosine (in rabbits). This acid has also been found in the urine 

 by SCHULTZEN and RIESS in acute yellow atrophy of the liver, and by 

 BAUMANN in phosphorus poisoning, although the earlier investigators 

 incorrectly considered the acid as oxymandelic acid. That this acid, 

 which was considered as oxymandelic acid, is Z-p-oxypbenyl-lactic acid 

 has been proved by ELLINGER and KOTAKE and FROMHERZ. S 



As shown especially by the investigations of O. NEUBAUER the demoli- 

 tion of the aromatic amino-acids passes ordinarily by way of the cor- 

 responding keto-acid. As stated above (page 737) in regard to the forma- 

 tion of homogentisic acid, the demolition of tyrosine, according to NEU- 

 BAUER, passes over the p-oxyphenylpyruvic acid, HO.CeH^CH^.CO.COOH. 

 According to him phenylamino-acetic add also yields phenylglyoxylic acid; 



1 Neubauer, Deutsch. Arch. f. klin. Med.,95; L. Blum, Arch.f. exp. Path. u. Pharm., 

 59; Flatow, Zeitschr. f. physiol. Chem., 64; F. Knoop, ibid., 67; Friedmann and 

 Maase, Bioch. Zeitschr., 27. 



2 Schotten, Zeitschr. f. physiol. Chem., 8; O. Neubauer, 1. c. 



3 Blendemann, Zeitschr. f. physiol. Chem., 6; Schultzen and Riess, Chem. Cdntralbl, 

 1869; Baumann, Zeitschr. f. physiol. Chem., 6; Ellinger and Kotake, ibid., 65; From- 

 herz, ibid., 70. 



