Full resolution (JPEG) - On this page / på denna sida - II. The Protein Substances - I. Simple Proteins - B. Albuminoids or Albumoids
<< prev. page << föreg. sida << >> nästa sida >> next page >>
Below is the raw OCR text
from the above scanned image.
Do you see an error? Proofread the page now!
Här nedan syns maskintolkade texten från faksimilbilden ovan.
Ser du något fel? Korrekturläs sidan nu!
This page has never been proofread. / Denna sida har aldrig korrekturlästs.
122 THE PBOTEIN SUBSTANCES.
According to Tebb reticulin is only a somewhat changed, impure collagen
but this is disputed by Siegfried. »
It may be prepared as follows, according to Siegfried: Digest intes-
tinal mucosa with trypsin and alkali. Wash the residue, extract with
ether, and digest again with trypsin and then treat with alcohol and ether.
On careful boiling with water the collagen present either as contamina-
tion or as a combination, with recticulin is removed. The thoroughly
boiled residue consists of reticulin.
Ichthylepidin is an organic compound, so-called by C. Morner,2
which occurs
with collagen in fish-scales and forms about one-fifth of their organic substance.
This compound, with 15.9 per cent nitrogen and 1.1 per cent sulphur, stands on
account of its properties rather close to elastin. . It is insoluble in cold and hot
water, as well as in dilute acids and alkalies at the ordinary temperature. On
boiling with these it dissolves. Pepsin-hydrochloric acid, as well as an alkaline
trypsin solution, also dissolves it. It responds beautifully to Millon’s reagent,
the xanthoproteic reaction, and the biuret test. At least a part of the sulphur
is split off «by the action of alkali. Ichthylepidin stands very close to elastin
in regard to its solubilities; but it differs essentially in composition as it is markedly
poorer in glycocoll, but much richer in proline and glutamic acid (Abderhalden
and Voitinovici 3
).
As skeletins, Krukenberg 4
has designated a number of nitrogenized
substances which form the skeletal tissue of various classes of inverte-
brates. These substances are chitin, spongin, conchiolin, byssus, cornein,
and crude silk {fibroin and sericin). Of these, chitin does not belong to
the protein substances, and silk is hardly to be classed as a skeletin.
Only those so-called skeletins will be discussed that actually belong to
the protein group, and chitin will be discussed in another chapter.
The elementary composition of certain of the bodies belonging to
this group is as follows :
5
C H N
Conchiolin (from the shells of pinna) .. . 52.70 G.54 1G.G0
Spongin 46.50 G.30 16.20
48.75 6.35 16.40
Cornein 48.96 5.90 16.81
Fibroin 48.23 6.27 18.31
" 48.30 6.50 19.20
Sericin 44.32 6.18 18.30
44.50 0.32 17.14
s
85
50
(Wetzel)
(Crookewitt)
(Posselt)
(Krukenberg)
(Cramer)
(Vignon)
(Cramer)
(Bondi)
1
Tebb, Journ. of Physiol., 27; Siegfried, ibid., 28.
2 Zeitschr. f. physiol. Chem., 24 and 37. See also Green and Tower, ibid., 35.
’ Zeitschr. f. physiol. Chem., 52, p. 368.
4
Grundziige einer vergl. Physiol, d. thier. Geriistsubst. Heidelberg, 1885.
• Krukenberg, Her. d. d. chem. Gesellsch., 17 and IS, and Zeitschr. f. Biologie, 22;
Croockewitt, Annal. d. Chem. u. Pharrn., 48; Posselt, ibid., 45; Cramer, Journ. f.
prakt. Chem., 96; Vignon, Compt. rend., 115; Wetzel, Zeitschr. f. physiol. Chem., 29
and CentralU. f. Physiol., 13, 113; Bondi, Zeitschr. f. physiol. Chem., 34.
<< prev. page << föreg. sida << >> nästa sida >> next page >>
