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TRYPTOPHANE. 155
hydrochloric acid, at the same time splitting off water. Recently he
has suggested another method which yields good rasults. Other syn-
theses of proline have also been performed by E. Fischer and Will-
statter. 1
By the reduction of the ethyl ester of pyrrolidon carboxylic
acid (see glutamic acid) E. Fischer and Boehner 2
have obtained racemic
a-proline. On putrefaction proline yields 5-amino-valeric acid and n-
valeric acid (Neuberg and Ackermann 3
).
/-Proline crystallizes in flat needles. It is readily soluble in water
and alcohol. The solution has a sweet taste; the specific rotation at
20° C. is (a) D = —77.40°. The solution acidified with sulphuric acid is
precipitated by phosphotungstic acid. In the detection of this acid
we make use of the copper salt, the anhydride of the phenylisocyanate
compound (melting-point 14-i°), and the picrate. The inactive acid and
its compounds show somewhat different properties.
Oxyproline (oxy-a-pyrolidine carboxylic acid), C5H9NO3. This acid,
whose constitution is not understood was first obtained by E. Fischer
on the hydrolysis of casein and of gelatin. It dissolves readily in water;
has a specific rotation of (a) D = —81.04°, and the solution has a sweet
taste. Oxyproline crystallizes in beautiful colorless plates and gives
a readily soluble copper salt. The constitution of natural oxyproline
has recently been explained by Leuchs and Brewster.4
They find
that the natural oxyproline is a 7-oxy-derivative of pyrrolidine-a-carbox-
ylic acid. Leuchs found the specific rotation of ^-oxyproline to be
(a) D =_76° at 20° C.
/-Tryptophane (indol-a-aminopropionic acid),
C.CH2 .CH(NH2 )COOH
CnHi2N202 = C6 H4<^CH
NH
is one of the cleavage products of the proteins formed in tryptic diges-
tion and other deep decompositions of the proteins, such as putrefaction,
cleavage with baryta-water or sulphuric acid. It gives a reddish-violet
product with chlorine or bromine which is called yroteinochrome. Nencki 5
considered tryptophane, which name is generally given to this acid,
as the mother-substance of various animal pigments.
1
Ber. d. d. chem.. Gesellsch., S3.
2
Ber. d. d. Chem., Gesellsch., 44.
’ Neuberg, Bioch. Zeitschr, 37; Ackermann, Zeitschr. of Biol., 57.
4
Fischer, Ber. d. d. chem. Gesellsch., 35 and 36; Leuchs and Brewster, Ber. d. d.
Chem., Gesellsch.. 46.
5
In regard to tryptophane, see Stadelmann, Zeitschr. f. Biologic, 26; Neumeister,
ibid., 26; Nencki, Ber. d. d. chem. Gesellsch.,’ 28; Beitler, ibid., 31; Kurajeff, Zeitschr.
f. physiol. Chem.. 26; King, Pfliiger’s Arch., 86.
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