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84 THE PROTEIN SUBSTANCES.
by Harries and Langheld j
and the action of chlorine by Habermann and
Ehrenfeld and Panzer. 2
Nitric acid gives various yellow products, which turn reddish-brown in
alkaline solution. Of these we must especially mention the so-called xantho-
protein, besides nitrated proteoses and peptones. The xanthoprotein does not
yield any tyrosine on acid hydrolysis and it does not give the Millon or the lead-
blackening reactions. Among the cleavage products v. Furth 2
has obtained a
melanoidin substance, xanthomelanoidin.
On the nitration of the protamines (see below) Kossel 4
and co-workers have
obtained nitroprotamines which give nitroarginine on hydrolysis which shows that
the nitro groups have entered the guanidine groups of the arginine.
By the dry distillation of proteins we obtain a large number of decomposition
products having a disagreeable burned odor, and a porous glistening mass of carbon
containing nitrogen is left as a residue. The products of distillation are partly
an alkaline liquid which contains ammonium carbonate and acetate, ammonium
sulphide, ammonium cyanide, an inflammable oil, and other bodies, and a brown
oil which contains hydrocarbons, nitrogenized bases belonging to the aniline and
pyridine series, and a number of unknown substances.
The occurrence of protein substances which contain a carbohydrate
group has been known for a long time. The nature of this carbohydrate,
which can be split off by acid and which may amount to as much as 35
per cent, has been explained chiefly by the investigations of Friedrich
MfJLLER 5 and his students. They have shown that it is always an
amino-sugar, and generally glucosamine and perhaps galactosamine
as |an exception. That so-called true proteins also yield a carbohydrate
on hydrolytic cleavage was first shown by Pavy, using ovalbumin. The
continued investigations of Fr. Muller, and others have demonstrated
that in these cases the carbohydrate is also glucosamine. A carbohy-
drate complex, although sometimes only to a very slight amount, has
been detected in other proteins, ovoglobulin, serglobulin, seralbumin,
peaglobulin, albumin of the gramineae, yolk-proteid, and fibrin. In
other proteins, on the contrary, such, as edestin (of the hemp-seed) and
casein, myosin, pure fibrinogen, and ovovitellin, carbohydrates have
been sought for with negative results. All proteins hence do not contain
a carbohydrate group, and future investigators must therefore decide
whether the carbohydrate groups belong positively to the protein com-
1
Blumenthal and Neuberg, Deutsch. med. Wochenschr., 1901; Orgler, Hofmeister’s
Beitrage, 1; Harries and Langheld, Zeitschr. f. physiol. Chem., 51.
2
Habermann and Ehrenfeld, Zeitschr. f. physiol. Chem., 32; Panzer, ibid., 33
and 34.
3
See Maly’s Jahresber, 30, p. 24.
4
Kossel and Kennaway, Zeitschr. f. physiol. Chem., 72, with E. Wechsler, ibid.,
78 and with F. Weiss, ibid., 78.
6
In regard to the literature on this subject see the work of Fr. Muller, Zeitschr.
f. Biologie, 42, and Langstein, Ergebnisse der Physiologie, Jahrg. I, Abt. 1, 63, Zeitschr.
f. physiol. Chem., 41, and Hofmeister’s Beitrage, 6. See also Abderhalden, Bergell,
and DOrpinghaus, Zeitschr. f. physiol. Chem., 41.
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