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EREPSIN. 493
Hekma, Falloise, and others, which, however, Delezenne says. 1
is
formed in the leucocytes and Peyer’s glands.
Erepsin. This enzyme, discovered by O. Cohnheim, has no direct
action upon native proteins with the exception of casein, but has the
power of splitting proteoses, peptones and certain polypeptides. In
this change mono- as well as diamino-acids are produced. Erepsin
occurs in the mucous membrane and in the intestinal juice of man as
well as of dogs; the mucous membrane seems to be richer than the juice
(Salaskin, Kutscher and Seemann 2
). An enz3me like erepsin also
occurs in the pancreas (Bayliss and Starling, Vernon), and this has
the power of acting upon casein, but not, or only faintly, upon fresh
fibrin. This erepsin is probably identical with the enzyme nvclease,
discovered by F. Sachs in the pancreas, which acts upon nucleic acids,
while Nakayama claims that erepsin differs from trypsin in having a
cleavage action upon nucleic acids. Intestinal erepsin is not inhibited,
according to Glaessner and Stauber, by blood-serum and differs in
this regard from trypsin. Erepsin shows a great similarity to the intra-
cellular enzymes active in autolysis, and according to Vernon and others
erepsins occur in the various tissues of invertebrates as well as verte-
brates. These tissue erepsins, which are closely related to the auto-
lytic enzymes, if they are not identical with them, behave somewhat
differently from the intestinal erepsin and are not identical therewith.
Enzymes, having an action similar to erepsin, occur, Vines believes,3
in all plants so far investigated.
Erepsin becomes inactive on heating to 59°. It works best in
alkaline solution, but has hardly any action in faint acid reaction. In
this regard, as well as by the fact that only a little ammonia is split off
by its action upon peptone substances, it differentiates itself from cer-
tain of the autolytic enzymes studied so far. The optimum of alkalinity
is, according to Euler,4
at least in the splitting of a polypeptide, much
lower than the optimum for tryptic digestion.
The secretion of the glands in the large intestine seems to con-
sist chiefly of mucus. Fistulas have also been introduced into these
1
Boldyreff, Arch. d. scienc. biolog, de St. Petersbourg, 11; Bayliss and Starling,
Journ. of Physiol., 29, 30; Hekma, 1. c; Falloise, see Biochem. Centralbl., 4, p. 153;
Vernon, Journ. of Physiol., 33; Delezenne, Compt. rend. soc. biolog., 54 and 56.
2
Cohnheim, Zeitschr. f. Physiol. Chem., 33, 35, 36, and 47; Salaskin, ibid., 35;
Kutscher and Seemann, ibid., 35.
* Bayliss and Starling, Journ. of Physiol., 30; Vernon, ibid., 30 and 33. See also
Cohnheim and Pletnew, Zeitschr. f. physiol. Chem. 69; F. Sachs, Zeitschr. f. physiol.
Chem., 46; Nakayama, ibid., 41; Glaessner and Stauber, Bioch. Zeitschr. 25; Vines,
Annals of Botany, 18, 19, and 23.
4
Zeitschr. f. physiol. Chem., 51
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