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136 THE PROTEIN SUBSTANCES.
is rather generally admitted that they are formed by a synthesis, a view
which has received support by the investigations of V. Henriques and
Gjaldbak.1
According to Sawjalow a plastein is not formed from a
proteose alone, but always from a mixture of proteoses. Lawrow claims
that they may be produced from proteoses as well as from polypeptide
substances, and correspondingly we must differentiate between the coag-
uloses or coagulosogens from the proteose group coaproteoses, and from
the polypeptide group or coapeptides. The latter yield on hydrolysis
chiefly monamino-acids, while the first yield also basic nitrogenous prod-
ucts. Perhaps the plasteinogen investigated by Bayer 2
which differs
essentially from the true proteid in its elementary composition as well
as from other coaguloses, belongs to the coapeptides.
The different behavior on saturating their solution with ammonium
sulphate has been generally used, as above remarked, for years to dif-
ferentiate between the proteoses and peptones. Those precipitable
by this salt were called proteoses, and those not were called peptones.
This method of division, which never had sufficient support and which
was perfectly arbitrary, cannot be considered at the present time. We
know now, thanks to the works of Emil Fischer and his co-workers,
that there are polypeptides either prepared artificially or found among
the cleavage products of the proteins, which are precipitated by ammo-
nium sulphate. At the present it is generally conceded that the peptones
in the ordinary sense are only a mixture of different bodies. The chief
step in these investigations must be the isolation from this mixture
of unit bodies with definite chemical characteristics. Of such bodies,
besides the polypeptides previously mentioned and studied by Fischer
and others, we must mention the products isolated by Siegfried and
his pupils.3
These so-called peptones are in part peptic-peptones and partly
tryptic-peptones, and some are prepared from proteid (fibrin) and others
from gelatin. The tryptic fibrin-peptones are antipeptones in Kuhne’s
sense because they are very resistant to the further action of trypsin.
They are according to Neumann simultaneously bibasic acids and mono-
acidic bases. They give the biuret reaction, but not Millon’s reaction;
they contain no tyrosine and yield on hydrolysis, arginine, lysine, glutamic
acid, and it seems also aspartic acid. A pepsin-glutin peptone isolated
by Siegfried and Schmitz yielded arginine, lysine, glutamic acid, gly-
1
Zeitschr. f. physiol. Chem., 71 and 81.
2
Hofmeister’s Beitriige, 4; see also L. Rosenfeld, ibid., 9; J. Lukomnik, ibid., 9
and F. Micheli, Biochem. Centralbl., 6, p. 562.
’ The works of Siegfried and his pupils, Fr. Muller, Borkel, Miihle, Kriiger, Scheer-
rnesser, Neumann, H. Schmitz, may be found in Arch. f. (Anat. u.) Physiol., 1894 and
Zeitschr. f. physiol. Chem., 21, 41, 43, 45, 48, 59, and 65 and Pfliiger’s Arch. 136.
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