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780 UKINE.
The aromatic amino-acids are, like the amino-acids in general, decom-
posed to fatty acids and have one carbon atom less. For example phenyl-
amino-acetic acid is in part converted into benzoic acid (O. Neubauer) ;
o- and ra-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 x
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
C6H5 .CH(OH).COOH
in the urine after feeding phenylaminoacetic acid, C6H5.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 acid, C6H5.CO.COOH.
As example of a hydrolytic deamidation we will use the production, as
first observed by Blendermann, of p-oxyphenyl-lactic acid,
HO.C6H4 .CH2 .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-oxyphenyl-lactic acid
has been proved by Ellinger and Kotake and Fromherz.3
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.CeH4.CH2.CO.COOH.
According to him phenylamino-acetic acid 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.
1,
Zeitschr., 27.
2
Schotten, Zeitschr. f. physiol. Chem., 8; O. Neubauer, 1. c.
3
Blendemann, Zeitschr. f. physiol. Chem., 6; Schultzen and Riess, Chem. Ctotralbl.,
1869; Baumann, Zeitschr. f. physiol. Chem., 6; Ellinger and Kotake, ibid., 65; From-
herz, ibid., 70.
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