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576 MUSCLES.
tion of creatine in water is not precipitated by basic lead acetate, but
gives a white, flaky precipitate with mercurous nitrate if the acid reac-
tion is neutralized. When boiled for an hour with dilute hydrochloric
acid, creatine is converted into creatinine, and may be identified by its
reactions. On boiling with formaldehyde it can be transformed into
dioxymethylenecreatinine, which crystallizes readily (Jaffe ’).
The preparation and detection of creatine is best accomplished by the
following method of Neubauer,2 which was first used in the preparation
of creatine from muscles: Finely cut meat is extracted with an equal
weight of water at 50-55° C. for 10-15 minutes, pressed, and extracted
again with water. The proteins are removed from the united extracts
so far as possible by coagulation at boiling heat, the filtrate precipitated
by the careful addition of basic lead acetate, the lead removed from this
filtrate by H2S, and the solution then carefully concentrated to a small
volume. The creatine, which crystallizes in a few days, is collected on a
filter, washed with alcohol of 88 per cent, and purified, when necessary,
by recrystallization. In the preparation of large quantities of creatine
we can especially start with meat extracts. The quantitative estimation
of creatine is performed by transforming it into creatinine (see Chapter
XIV).
Carnosine, C9H14N4O3, is a base first isolated by Gulewitsch and
Amiradzibi from meat extracts and which subsequently was also pre-
pared directly from meat. The quantity seems to be relatively consider-
able, as according to the above-mentioned determination of v. Furth*
and Schwarz, the carnosine fraction from the horse and dog muscles
was just as large or indeed greater than the creatine-creatinine fraction
of the extractive nitrogen. Krimberg found 1.3 p. m. and Skworzow,3
1.76 p. m. (as nitrate) in fresh meat.
Carnosine, which according to Gulewitsch is identical with the base
ignotine isolated from meat extracts by Kutscher while both bases are
isomeric bodies according to Kutscher,4 is a histidine derivative accord-
ing to Gulewitsch which on cleavage yields /3-alanine besides histidine.
Carnosine is a base readily soluble in water, which is precipitated
as stellar warts of short delicate needles from the concentrated watery
solution by the addition of alcohol. The specific rotation for the light
X = 546 is according to Gulewitsch in watery solution where c = 12.925
per cent and 20.1° C. = -r-25.3°. The base is precipitated by phospho-
1
Ber. d. d. Chem. Gesellsch., 35.
2
Zeitschr. f. analyt. Chem., 2 and 6.
’Gulewitsch and Amiradzibi, Zeitsdir. f. physiol. Chem., 30; Gulewitsch, ibid.,
50, 51, 52 and 73; Krimberg. ihid., 48; Skworzow, ibid., 68.
4
Gulewitsch and Amiradzibi, Zeitschr. f. physiol. Chem., 30; Gulewitsch, ibid., 50,
51, 52 and 73; Krimberg, ibid., 08; Skworzow, ibid., 68; Kutscher, ibid., 50, 51.
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