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PROTEOSES .WD PEPTONES. 131
BUggeste the following.1
The primary proteoses are precipitated by
nitric arid in salt-free solutions, while the secondary proteoses arc pre-
cipitated only in salt solutions, and certain deuteroproteoses, such as
deuterovitellose and deuteramyosinose, are precipitated by nitric acid
only in solutions saturated with Na( ’1. The primary proteoses arc pre-
cipitated from neutral solutions by copper-sulphate solution (2:100),
and by NaCl in substance, while the secondary proteoses are not. The
primary proteoses are completely precipitated from a solution saturated
with NaCl by the addition of acetic acid saturated with salt, while the
secondary proteoses arc only partly precipitated. The primary proteoses
are readily precipitated by acetic acid and potassium ferrocyanide, while
the secondary are only incompletely precipitated after some time. The
primary proteoses are also, according to Pick,2
completely precipitated
by ammonium sulphate (added to one-half saturation), while the second-
ary proteoses remain in solution.
The true peptones, as they were formerly considered to be, are exceed-
ingly hygroscopic, and if perfectly dry, sizzle like phosphoric anhydride
when treated with a little water. They are exceedingly soluble in water,
diffuse more readily than the proteoses, and are not precipitated by
ammonium sulphate. In contradistinction to the proteoses, the true
peptones are not precipitated by nitric acid (even in solutions saturated
with salt), by sodium chloride and acetic acid saturated with salt,
potassium ferrocyanide and acetic acid, picric acid, trichloracetic
acid, potassium-mercuric iodide, and hydrochloric acid. They are
precipitated by phosphotungstic acid, phosphomclybdic acid, corrosive
sublimate (in the absence cf neutral salts), absolute alcohol, and tannic
acid, but the precipitate may redissolve on the additicn of an excess of
the precipitant. As an important difference between amphopeptone and
antipeptone we must also mention that the former gives Millon’s
reaction, while the antipeptone does not.
In regard to the precipitation by alcohol we must call attention to the observa-
tions of Frankel that not only are the acid combinations of peptone (Paal)
soluble in alcohol, but also the free peptone, and Frankel has even suggested a
method of preparation based on this behavior. Schrotter 3
has also prepared
crystalline proteoses which were soluble in hot alcohol, especially methyl alcohol.
The views on the hydrolytic cleavage products of peptic and tryptic
digestion which were accepted until a few years ago have recently been
considerably modified in several points.
1
Xeumeister, Zeitschr. f. Biologic, 24 and 26.
2
Zeitschr. f. physiol. Chem., 24.
3
Frankel, Zur Kenntnis der Zerfallsprodukte des Eiweisses bei peptischer und
tryptiecher Verdauung, Wien, 1896; Schrotter, Monatshefte f. Chem., 14 and 16.
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