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PROTEOSES AM) PEPTONES. 137
cocoll and besides these also leucine and proline although not in quan-
tities that could be determined. Of the total nitrogen they found
i’9-7 per cent arginine, 9.1 per eent lysine, 19.2 per cent glycocoll, 9.3
percenl glutamic acid and 12.7 per cent proline and leucine together.
Siegfried has given proof in several ways as to the purity and unity
of the peptones isolated by him.
In another manner, namely by fractional precipitation with metallic salts,
especially with mercuric-potassium iodide and the preparation of phenyliso-
cyanate compounds, Hofmeister and his pupils Stookey, Raper and Rogo-
zinski i have isolated peptones or polypeptide-like bodies from blood proteid.
One of these, called arginine-histidine peptone, yielded arginine and histidine as
basic hydrolytic products while another yielded chiefly lysine^as basic product
and hence was called lysine-peptone.
From glutin-pcptone, Siegfried, on warming with hydrochloric
acid, obtained a base, C21H39N9O8, which can also be directly obtained
from gelatin. This he calls a kyrin, because it is to be considered as a
basic protein nucleus, and he calls this special one glutokyrin. The
glutokyrin gives the biuret reaction and is considered as a basic peptone.
On complete hydrolytic cleavage it yields arginine, lysine, glutamic
acid, and glycocoll. Of the total nitrogen two-thirds belong to the
bases and one-third to the amino-acids. Recently he with 0. Pilz
on further hydrolysis has prepared a /3-glutokyrin, which only yielded
arginine, lysine and glutamic acid. Similar basic nuclei, protokyrins,
have recently been obtained by Siegfried 2
from fibrin and casein, using
the same method. Caseinokyrin gives a non-crystalline sulphate, but
a crystalline phosphotungstate. The free caseinokyrin has an alkaline
reaction, gives the biuret test, and its composition corresponds to the
formula C23H47N9O8. It yields arginine, lysine, and glutamic acid on
cleavage. The basic nitrogen amounts to about 85 per cent of the total
nitrogen, and caseinokyrin, behaves in this respect like a protamine.
Among the known cleavage products of proteins, arginine is the only
one which, up to the present, is never absent, and for this reason Ave
designate as proteins only those atomic complexes which contain, besides
chained monamino-acids, also arginine, or, more simply, show the prev-
iously mentioned imide bindings. Hence caseinokyrine, which yields
only arginine, lysine and glutamic acid, and scombrin, which yields
only arginine, proline, and alanine, are the simplest known proteins.
Scombrin belongs to the previously mentioned group of protamines
which, according to Kossel,3
are formed by a successive cleavage of the
1
Hofmeister’s Beitrage, 7, 9, and 11.
2
Kgl. Sachs. Ges. d. Wiss., Math.-Phys. Klasse, 1903, and Zeitschr. f. phvsiol
Chem., 43, with Pilz., ibid., 58.
3
Zeitschr. f. phvsiol. Chem., 44.
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