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16a THE PROTEIN SUBSTANCES.
Abderhalden found 10.96 per cent. It also occurs in germinating plants
(E. Schulze x
).
Histidine has been prepared synthetically by Pyman. 2
4 (5) chlormethyl
glyoxalin yields with sodium chlormalonic ester the glyoxalinmethylchlormalonic
ester.
CH.NHx
II
>
C N^
CH2 .CC1(C02 .C2 H6 ) 2
>CH , which on
hydrolysis gives cW-a-chlor-/3-glyoxalin-4 (5) propionic acid,
CH—NHs
>>CH
C N
CH2 CHCI.COOH
This latter treated with NH3 yields d-Z-histidine, which is changed into the active
forms by means of tartaric acid.
In the anaerobic putrefaction of histidine, /3-imidazolylethylamine
and imidazolylpropionic acid are formed (Ackermann 3
).
Histidine crystallizes in colorless needles and plates and is readily
soluble in water, but less soluble in alcohol, and has an alkaline reaction.
It is precipitated by phosphotungstic acid, but this precipitate is soluble
in an excess of the precipitant (Frankel). With silver nitrate alone
the aqueous solution is not precipitated; on the careful addition of
ammonia or baryta-water an amorphous precipitate, which is readily
soluble in an excess of ammonia, is obtained. Histidine can be pre-
cipitated by mercuric chloride, or, still better, by the sulphate acidified
with sulphuric acid, and can in this way be separated from the other
diamino-acids (Kossel and Patten). The hydrochloride crystallizes in
beautiful plates (Bauer), dissolves rather readily in water, but is insolu-
ble in alcohol and ether. With hydrochloric acid and methyl alcohol
it gives the dihydrochloride of histidine methyl ester, which melts at
196°. Histidine is lsevorotatory, (a) D = —39.74°, while its solution in
hydrochloric acid is dextrorotatory. On warming it gives the biuret test
(Herzog), and it also gives Weldel’s reaction if performed as sug-
gested by Fischer (see Xanthine, Chapter V) (Frankel 4
). On adding
1
Kossel, Zeitsflir. f. physiol. Chem., 22; Hedin, ibid., Kutscher, ibid., 25; Wetzel,
ibid., 26; Lawrow, ibid., 28, and Ber. d. d. chem. Gesellsch., 34; Kossel and Kutscher,
Zeitschr. f. physiol. Chem., 31; Hart, ibid., 33; Abderhalden, ibid., 37; Schulze, ibid. r
24 and 28.
-
Cited from Chem. Centralbl., 1911, 2, p. 760.
3
Zeitsr-lir. f. physiol. Chem., 65.
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