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774 URINE.
acid having two carbon atoms less takes place according to this assump-
tion according to the formula:
R.CH2 .CH2 .COOH-*R.CH(OH).CH2.COOHR.CO.CH2.COO±^H->
R.COOH.
The animal body has therefore the ability to transform oxyacids (alcohol
acids) into keto-acids by oxidation as well as the reverse, the conversion
of keto-acids into oxyacids, and this behavior, which is indicated by the
above formula, makes it difficult to state which products are primary
and which are secondary. As example of such a reversible process we
will mention the following; the 0-oxybutyric acid CH3 .CH(OH).CH2 COOH
is transformed by oxidation into the keto-acid, acetoacetic acid,
CH3.CO.CH2COOH, and this latter by reduction is changed into /3-
oxybutyric acid. Both processes may take place, as Friedmann and
Maase, Dakin and Wakeman * have shown, in the liver, and as these
two so-called acetone bodies have great importance in diabetes, they
may serve also as an example of the first stages of a ^-oxidation (of
n. butyric acid).
Most of the investigations on the demolition of fatty acids have been
carried out by Knoop, Dakin, Friedmann and others upon substituted,
especially phenyl-substituted fatty acids, and in speaking of the behavior
of the cyclic compounds we will discuss the behavior of these.
The amino-acids are, when large amounts are introduced into the
animal body, eliminated unchanged, and even under physiological con-
ditions traces of the amino-acids formed in the animal body can pass
into the excretions—glycocoll in the urine and serine in the perspiration.
Otherwise they are as a rule decomposed and a deamidation takes place,
the ammonia split off serving for material for the formation of urea.
The two components of a racemic a-amino-acid behave differently in that
the alien component is burned with greater difficulty and less completely
than the component occurring in the body protein, which is burned
more readily and more completely.
In the demolition of the a-amino-acids, fatty acids, poorer in carbon,
are formed; the detailed manner of this demolition has been explained
in various ways.
According to a long-accepted view it was believed that a hydrolytic
splitting off of ammonia with the formation of the corresponding oxyacid
(alcohol acid) took place, according to the formula R.CHNH2.COOH-f-
H2 = R.CH(OH).COOH+NH3 , and then a further demolition to
1
Friedmann and Maase, Bioch. Zeitschr., 27; Dakin and Wakeman, Journ. of biol.
Chem., 8.
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