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530 DIGESTION.
the other hand it is not possible to deny the importance of the liver for
the protein syntheses. As Embden and his collaborators have shown on
perfusing the liver containing a large amount of glycogen, that d-alanine
was formed and Embden explains this formation by a destruction of
glucose or lactic acid and pyroracemic acid. With experiments with
blood perfusion of the liver, a-amino-acids are formed from the am-
monium salts of the corresponding a-keto-acids. The combination
NH4.O.CO.CO.R passes into HO.CO.CH(NH2 ).R. The cleavage
products of the carbohydrates can be converted in the liver into char-
acteristic constituents of the protein molecule.1
In this connection
we must here mention the experiments of Luthje 2
in which he found
a nitrogen retention after feeding only one amino-acid with abundance
of carbohydrate.
What kind of protein is formed in the synthesis? This we do not
know. Abderhalden’s belief is that it is plasma protein, which, as
is well known, is the same in each animal independent of the kind of
protein introduced with the food and from which the cells of the body
then create the further protein material. Objections can be raised
against this hypothesis, but still it is worth consideration. In favor
of this we can also add that according to the investigations of Freund
and v. Korosy 3
the blood coming from the intestine during digestion
is richer in coagulable protein than other blood, and also that this
protein, Freund asserts, belongs to the globulin group. This globulin,
according to Freund and Toepfer, is not identical with the ordinary
serglobulin mixture, but is a pseudoglobulin formed in the. intestine
from the food protein by synthesis, and which is more easily decom-
posed or further utilized in the liver and other organs. Further research
in this direction is necessary, as we have other investigations which
are essentially different. If a re-formation of coagulable proteins takes
place from amino-acids during digestion, it is to be expected that a
relatively greater quantity of coagulable protein should occur in the
mucosa of the digesting intestine as compared with the non-digesting
intestine. Pringle and Cramer, by a method which requires con-
firmation, claim that in the digesting animal (cat), the blood, and to a
still higher degree the intestinal mucosa, and especially the lymph nodes
of the intestine, are richer in non-coagulable protein than the starving
animal, a condition which is related to the r61e of the leucocytes in the
iBioch. Zeitschr. 29, 423 (1910); 38, ’393, 407, 414 (1911); 45, 1-207 (1912);
summary, 45, 201.
2
Pfliiger’s Arch. 113, 547 (1906).
a
v. Korosy, Zeitschr. f. physiol. Chem., 57; Freund, Zeitschr. f. exp. Path. u.
Therap., 4; G. Toepfer and Freund, and Toepfer, ibid., 3; Pringle and Cramer, Journ.
of Physiol., 37.
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