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DEMOLITION OF AROMATIC FATTY ACIDS. 781
the m-tyrosine passes according to Flatow l
in part as ra-oxyphenyl
pyruvic acid in the urine. The keto-acids give also the same end products
as the corresponding amino-acids. Thus o-tyrosine, like o-oxyphenyl-
pyruvic acid, yields o-oxyphenylacetic acid (Flatow) as end product;
the i>-chlnrph< ni/lalanine and the p-chlorphcnylpijrui>ic acid pass into the
p-chlorphenylacetic acid, which is not the case with the oxyacid, the p-chlor-
phenyl-lactic acid (Friedmann and Maase 2
) . This last-mentioned case is
an example of the more ready combustibility of the keto-acids as com-
pared to the oxyacids. Another such example is the p-oxyphenyl pyruvic
acid, which is in great part burned, while the p-oxyphenyl-lactic acid is
hardly burned at all (Kotake, Suwa). A correspondingly different
behavior is shown by these two acids in perfusion experiments with
the excised liver of the dog. The oxyphenylpyruvic acid, like tyrosine,
shows itself to be an acetone former while oxyphenyl-lactic acid, on
the contrary, does not (Neubauer and Gross, E. Schmitz 3
). The
ready combustibility of the keto-acids indicate that these acids and
not the oxyacids are the important intermediary cleavage products.
In regard to the demolition of aromatic fatty acids, Knoop 4
has found
that the acids with even carbon chains, such as phenyl butyric acid and
phenyl caproic acid, are converted into phenylacetic acid, which con-
jugates with glycocoll to form phenaceturic acid, while the acids with
uneven carbon ’ chains, like phenylpropionic and phenylvaleric acid,
yield benzoic acid, which then is eliminated as hippuric acid. This
behavior is in close agreement with the generally accepted oxidation of
fatty at the /3-group, for which Dakin has also given important support.
Thus Dakin found after feeding phenylpropionic acid to cats, that
phenyl-&-cx])propionic add, benzoylacetic acid and acetophenone, the latter
passing into benzoic acid or hippuric acid, wT
ere formed, which pre-
supposes an oxidation in the /3-position. According to the investigations
of Dakin and Friedmann 5
the conditions are still very complicated.
Certain of the processes are reversible, oxidations as well as reductions
occur, and a-/3-unsaturated acids may also be formed as intermediary
products. Dakin as well as Friedmann have obtained cinnamic acid
as intermediary product in the demolition of phenylpropionic acid, and
1
Neubauer, Deutsch. Arch. f. klin. Med., 95; Flatow, Zeitschr.f. physio! . Chem., 6-4.
1
Flatow, 1. c; Friedmann and Masse, Bioch. Zeitschr., 27.
5
Kotake, Zeitschr. f. physiol. Chem., 69; Suwa, ibid., 72; Neubauer and Gross,
ibid., 67; Schmitz. Bioch. Zeitschr., 28.
4
Hofmeister’s Beitrage, 6, and Habilit.-Schrift, Freiburg, 1904.
6
Dakin, Journ. of biol. Chem., 4, 5, 6, 8, and 9; Friedmann, 6ee Med. Klinik,.
No. 28, 1911, and Bioch. Zeitschr., 35.
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