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INDOL AND SKATOL. 157
(«)d= —30.33°. Hopkins and Cole give (a) D =-33° for the watery
N N N
solution. It is dextrorotatory in — or — NaOH as well as in — HC1.
\ z 1
Tryptophane yields indol and skatol when sufficiently heated. It
gives the Adamkiewicz-Hopkins * reaction and a rose-red color on the
addition of chlorine or bromine water (tryptophane reaction). The
brom-tryptophane is readily soluble in amyl alcohol or acetic ether
and on shaking with these solvents the reaction is more delicate.2
If
a pine stick previously moistened with hydrochloric acid and washed
with water is introduced into a concentrated tryptophane solution,
it becomes purple (pyrrole reaction) on drying. The melting-points
of the benzoylsulphotryptophane, the /3-naphthalenesulphotryptophane
and the naphthylisocyanatetryptophane are according to Ellinger
and Flamand,3 185°, 180° and 158° C. respectively. Several compounds
of tryptophane have been prepared by Abderhalden and Kempe.4
Among these we will mention the tryptophane chloride hydrochloride,
because it is used as the starting material for the synthesis of trypto-
phane polypeptides. In the alcoholic fermentation of sugar, as found
by F. Ehrlich 5 the tryptophane present is transformed into tryptophol
(/3-indoxylethyl alcohol).
In regard to the rather complicated method for preparing trypto-
phane we must refer to the original work of Hopkins and Cole, of
Neuberg, and of Abderhalden and Kempe. Fasal 6
has suggested a
quantitative colorimetric method for estimating tryptophane based
upon the Adamkiewicz-Hopkins reaction.
As shown by Hopkins and Cole,7
tryptophane on anaerobic putre-
faction yields indolpropionic acid and indolacetic acid, and indol and
skatol on aerobic putrefaction. Among these putrefactive products the
indol and skatol will be specially discussed.
CH
Indol, C8H7 N = C6H4 <^\CH, and Skatol, or /3-methylindol,
NH
1
In regard to this reaction see also Dakin, Journ. of Biol. Chem. 2, and O. Rosen-
heim, Biochem. Journ., 1.
2
Neuberg, Bioch. Zeitschr., 24.
»1. c.
4
Zeitschr. f. physiol. Chem., 52, and Ber. d. d. chem. Gesellsch., 40.
5
Ber. d. d. chem., Gesellsch., 45.
6
Hopkins and Cole. Journ. of Physiol., 27 and 29; Neuberg and Popowsky, Biochem.
Zeitschr., 2; Abderhalden and Kempe, Zeitschr. f. physiol. Chem., 52; Fasal, Bioch.
Zeitschr., 44.
7
Journ. of Physiol., 29.
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