Full resolution (JPEG) - On this page / på denna sida - II. The Protein Substances - I. Simple Proteins - C. Cleavage Products of Simple Proteins - 3. The Amino-acids
<< prev. page << föreg. sida << >> nästa sida >> next page >>
Below is the raw OCR text
from the above scanned image.
Do you see an error? Proofread the page now!
Här nedan syns maskintolkade texten från faksimilbilden ovan.
Ser du något fel? Korrekturläs sidan nu!
This page has never been proofread. / Denna sida har aldrig korrekturlästs.
TAURINK. 151
origin from proteins has been shown by Friedmann by the close rela-
tion that taurine bears to cysteine; and this is the reason why it is
treated here in connection with the amino-acids.
Taurine is especially known as a cleavage product of taurocholic
acid, and may occur to a slight extent in the intestinal contents. Taurine
has also been found in the lungs and kidneys of oxen and in the blood
and muscles of cold-blooded animals.
Taurine crystallizes in colorless, often in large, shining, 4- or 6-sided
prisms. It dissolves in 15-16 parts of water at ordinary temperatures,
but rather more easily in warm water. It is insoluble in absolute alcohol
and ether; in cold alcohol it dissolves slightly, but better when warm.
Taurine yields acetic and sulphurous acids, but no alkali sulphides,
on boiling with strong caustic alkali. The content of sulphur can be
determined as sulphuric acid after fusing with saltpeter and soda.
Taurine combines with metallic oxides. The combination with mercuric
oxide is white, insoluble, and is formed when a solution of taurine is boiled
with freshly precipitated mercuric oxide (J. Lang 1
). This compound
may be used in detecting the presence of taurine. Taurine is not pre-
cipitated b}r
metallic salts.
The preparation of taurine from ox-bile is very simple. The bile
is boiled a few hours with hydrochloric acid. The filtrate from the
dyslysin and choloidic acid is concentrated well on the water-bath, and
filtered hot so as to remove the common salt and other substances which
have separated. The solution is evaporated to dryness and the residue
dissolved in 5 per cent hydrochloric acid, and precipitated with 10 vols.
95 per cent alcohol. The crystals are readily purified by recrystalliza-
tion from water.
The acid alcoholic solution can be used for the preparation of glycocoll. After
the evaporation of the alcohol, the residue is dissolved in water, treated with a
solution of lead hydroxide, filtered, the lead removed by H2 S, and the filtrate
strongly concentrated. The crystals which separate are dissolved and decolor-
ized by animal charcoal and the solution then evaporated to crystallization.
Though taurine shows no positive reactions, it is chiefly identified
by its crystalline form, by its solubility in water and insolubility in
alcohol, by its combination with mercuric oxide, by its non-precipitability
by metallic salts, and above all by its sulphur content.
/-Phenylalanine (phenyl-a-aminopropionic acid),
C6 H5
CH2.
C9HnN02 = CH(NH2)i
COOH
1
See Maly’s Jahresber, 6.
<< prev. page << föreg. sida << >> nästa sida >> next page >>
