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77G URINE.
The residue of the amino-acids remaining after deamidation can
naturally, according to the rule governing the fatty acids, be burned
and in certain cases this combustion takes place with the formation of
acetone bodies (which see). The fatty acid residue can also be used, be-
sides in the synthesis of amino-acids, also in the synthesis of other
substances, and in Chapter VII the formation of carbohydrates from
amino-acids has been mentioned.
Among the amino-acids the cystine, or better the cysteine,
CH2 . (SH) .CH (NH2) .COOH,
show a special behavior. On oxidation in the SH group and splitting
cff of CO2 (see page 149) it is transformed into a new amino-acid, taurine
(H2N)CH2.CH2(S020H). Taurine,.which when conjugated with cholic acid
forms taurocholic acid, occurring in the bile and which is habitually decom-
posed in the intestine or other parts of the animal body, can when intro-
duced as such into the human body, at least in part, be eliminated in
the urine as such or as tauro-carbamic acid, H2N.CO.NH.C2H4.SO2OH
(Salkowski l
). Otherwise as end-products of the demolition of cystine
and taurine an increased elimination of urinary sulphur, sulphuric acid and
thiosulphate, have been observed (Blum, Abderhalden and Samuely 2
).
The sulphydryl group of cysteine also serves in the formation of sulpho-
cyanide, which is formed from the nitriles, introduced into the animal
body, by the HCN (Lang). The loosely combined sulphur of the pro-
teins, according to the observations of Pascheles, in alkaline reaction and
body temperature, can be readily transformed, with the cyan alkali into
sulphocyanide alkali. The alkali sulphocyanides when ingested are
almost quantitatively eliminated in the urine, according to Pollak.3
By substituting one of the hydrogen atoms in the NH2 group of
normal a-amino-acids by an alkyl radical (methyl) the combustion of the
acids of the series C2 and C4 is considerably retarded and almost entirely
prevented in the members of the C5 and C6 series (Friedmann).4
Sar-
cosine (methyl glycocoll), (CH3)NH.CH2.COOH, is not readily burnt, and
therefore passes in great part unchanged into the urine, but perhaps also
passes in small part into the corresponding uramino-acid, methylhydan-
toic acid, NH2.CO.N(CH3 ).CH2 .COOH (Schultzen 5
), is an example
1
Ber. d. d. Chem. Gesellsch., 6, and Virchow’s Arch., 58.
’ Bhjm, Hofmeister’s Beitrage, 5; Abderhalden and Samuely, Zeitschr. f. physiol.
Chem., 46.
’ Lang, Arch. f. exp. Path. u. Pharm., 34; Pascheles, ibid.; Pollak, Hofmeister’s
Beitrage, 2.
4
Hofmeister’s Beitrage, 11.
6
Ber. d. d. Chem. Gesellsch., 5. See also Baumann and v. Mering, ibid., 8, and
E. Salkowski, Zeitschr. f. physiol. Chem., 4.
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